| Message ID | 20180116005906.GA5434@fergus.ozlabs.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 16/01/2018 01:59, Paul Mackerras wrote: > This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace > information about the underlying machine's level of vulnerability > to the recently announced vulnerabilities CVE-2017-5715, > CVE-2017-5753 and CVE-2017-5754, and whether the machine provides > instructions to assist software to work around the vulnerabilities. > > The ioctl returns two u64 words describing characteristics of the > CPU and required software behaviour respectively, plus two mask > words which indicate which bits have been filled in by the kernel, > for extensibility. The bit definitions are the same as for the > new H_GET_CPU_CHARACTERISTICS hypercall. > > There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which > indicates whether the new ioctl is available. > > Signed-off-by: Paul Mackerras <paulus@ozlabs.org> > --- > Documentation/virtual/kvm/api.txt | 46 +++++++++++++ > arch/powerpc/include/uapi/asm/kvm.h | 22 +++++++ > arch/powerpc/kvm/powerpc.c | 124 ++++++++++++++++++++++++++++++++++++ > include/uapi/linux/kvm.h | 3 + > 4 files changed, 195 insertions(+) > > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt > index f670e4b..85ca84a 100644 > --- a/Documentation/virtual/kvm/api.txt > +++ b/Documentation/virtual/kvm/api.txt > @@ -3394,6 +3394,52 @@ invalid, if invalid pages are written to (e.g. after the end of memory) > or if no page table is present for the addresses (e.g. when using > hugepages). > > +4.108 KVM_PPC_GET_CPU_CHAR > + > +Capability: KVM_CAP_PPC_GET_CPU_CHAR > +Architectures: powerpc > +Type: vm ioctl > +Parameters: struct kvm_ppc_cpu_char (out) > +Returns: 0 on successful completion > + -EFAULT if struct kvm_ppc_cpu_char cannot be written > + > +This ioctl gives userspace information about certain characteristics > +of the CPU relating to speculative execution of instructions and > +possible information leakage resulting from speculative execution (see > +CVE-2017-5715, CVE-2017-5753 and CVE-2017-5754). The information is > +returned in struct kvm_ppc_cpu_char, which looks like this: > + > +struct kvm_ppc_cpu_char { > + __u64 character; /* characteristics of the CPU */ > + __u64 behaviour; /* recommended software behaviour */ > + __u64 character_mask; /* valid bits in character */ > + __u64 behaviour_mask; /* valid bits in behaviour */ > +}; > + > +For extensibility, the character_mask and behaviour_mask fields > +indicate which bits of character and behaviour have been filled in by > +the kernel. If the set of defined bits is extended in future then > +userspace will be able to tell whether it is running on a kernel that > +knows about the new bits. > + > +The character field describes attributes of the CPU which can help > +with preventing inadvertent information disclosure - specifically, > +whether there is an instruction to flash-invalidate the L1 data cache > +(ori 30,30,0 or mtspr SPRN_TRIG2,rN), whether the L1 data cache is set > +to a mode where entries can only be used by the thread that created > +them, whether the bcctr[l] instruction prevents speculation, and > +whether a speculation barrier instruction (ori 31,31,0) is provided. > + > +The behaviour field describes actions that software should take to > +prevent inadvertent information disclosure, and thus describes which > +vulnerabilities the hardware is subject to; specifically whether the > +L1 data cache should be flushed when returning to user mode from the > +kernel, and whether a speculation barrier should be placed between an > +array bounds check and the array access. > + > +These fields use the same bit definitions as the new > +H_GET_CPU_CHARACTERISTICS hypercall. > + > 5. The kvm_run structure > ------------------------ > > diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h > index 61d6049..ce74bed 100644 > --- a/arch/powerpc/include/uapi/asm/kvm.h > +++ b/arch/powerpc/include/uapi/asm/kvm.h > @@ -443,6 +443,28 @@ struct kvm_ppc_rmmu_info { > __u32 ap_encodings[8]; > }; > > +/* For KVM_PPC_GET_CPU_CHAR */ > +struct kvm_ppc_cpu_char { > + __u64 character; /* characteristics of the CPU */ > + __u64 behaviour; /* recommended software behaviour */ > + __u64 character_mask; /* valid bits in character */ > + __u64 behaviour_mask; /* valid bits in behaviour */ > +}; > + > +/* > + * Values for character and character_mask. > + * These are identical to the values used by H_GET_CPU_CHARACTERISTICS. > + */ > +#define KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 (1ULL << 63) > +#define KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED (1ULL << 62) > +#define KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 (1ULL << 61) > +#define KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 (1ULL << 60) > +#define KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV (1ULL << 59) > + > +#define KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY (1ULL << 63) > +#define KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR (1ULL << 62) > +#define KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR (1ULL << 61) > + > /* Per-vcpu XICS interrupt controller state */ > #define KVM_REG_PPC_ICP_STATE (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0x8c) > > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c > index 1915e86..c9cecff 100644 > --- a/arch/powerpc/kvm/powerpc.c > +++ b/arch/powerpc/kvm/powerpc.c > @@ -39,6 +39,10 @@ > #include <asm/iommu.h> > #include <asm/switch_to.h> > #include <asm/xive.h> > +#ifdef CONFIG_PPC_PSERIES > +#include <asm/hvcall.h> > +#include <asm/plpar_wrappers.h> > +#endif > > #include "timing.h" > #include "irq.h" > @@ -548,6 +552,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > #ifdef CONFIG_KVM_XICS > case KVM_CAP_IRQ_XICS: > #endif > + case KVM_CAP_PPC_GET_CPU_CHAR: > r = 1; > break; > > @@ -1759,6 +1764,117 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, > return r; > } > > +#ifdef CONFIG_PPC_BOOK3S_64 > +/* > + * These functions check whether the underlying hardware is safe > + * against attacks based on observing the effects of speculatively > + * executed instructions, and whether it supplies instructions for > + * use in workarounds. The information comes from firmware, either > + * via the device tree on powernv platforms or from an hcall on > + * pseries platforms. > + */ > +#ifdef CONFIG_PPC_PSERIES > +static int pseries_get_cpu_char(struct kvm_ppc_cpu_char *cp) > +{ > + struct h_cpu_char_result c; > + unsigned long rc; > + > + if (!machine_is(pseries)) > + return -ENOTTY; > + > + rc = plpar_get_cpu_characteristics(&c); > + if (rc == H_SUCCESS) { > + cp->character = c.character; > + cp->behaviour = c.behaviour; > + cp->character_mask = KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 | > + KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED | > + KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 | > + KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 | > + KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV; > + cp->behaviour_mask = KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY | > + KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR | > + KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR; > + } > + return 0; > +} > +#else > +static int pseries_get_cpu_char(struct kvm_ppc_cpu_char *cp) > +{ > + return -ENOTTY; > +} > +#endif > + > +static inline bool have_fw_feat(struct device_node *fw_features, > + const char *state, const char *name) > +{ > + struct device_node *np; > + bool r = false; > + > + np = of_get_child_by_name(fw_features, name); > + if (np) { > + r = of_property_read_bool(np, state); > + of_node_put(np); > + } > + return r; > +} > + > +static int kvmppc_get_cpu_char(struct kvm_ppc_cpu_char *cp) > +{ > + struct device_node *np, *fw_features; > + int r; > + > + memset(cp, 0, sizeof(*cp)); > + r = pseries_get_cpu_char(cp); > + if (r != -ENOTTY) > + return r; > + > + np = of_find_node_by_name(NULL, "ibm,opal"); > + if (np) { > + fw_features = of_get_child_by_name(np, "fw-features"); > + of_node_put(np); > + if (!fw_features) > + return 0; > + if (have_fw_feat(fw_features, "enabled", > + "inst-spec-barrier-ori31,31,0")) > + cp->character |= KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31; > + if (have_fw_feat(fw_features, "enabled", > + "fw-bcctrl-serialized")) > + cp->character |= KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED; > + if (have_fw_feat(fw_features, "enabled", > + "inst-l1d-flush-ori30,30,0")) > + cp->character |= KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30; > + if (have_fw_feat(fw_features, "enabled", > + "inst-l1d-flush-trig2")) > + cp->character |= KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2; > + if (have_fw_feat(fw_features, "enabled", > + "fw-l1d-thread-split")) > + cp->character |= KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV; > + cp->character_mask = KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 | > + KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED | > + KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 | > + KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 | > + KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV; > + > + if (have_fw_feat(fw_features, "enabled", > + "speculation-policy-favor-security")) > + cp->behaviour |= KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY; > + if (!have_fw_feat(fw_features, "disabled", > + "needs-l1d-flush-msr-pr-0-to-1")) > + cp->behaviour |= KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR; > + if (!have_fw_feat(fw_features, "disabled", > + "needs-spec-barrier-for-bound-checks")) > + cp->behaviour |= KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR; > + cp->behaviour_mask = KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY | > + KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR | > + KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR; > + > + of_node_put(fw_features); > + } > + > + return 0; > +} > +#endif > + > long kvm_arch_vm_ioctl(struct file *filp, > unsigned int ioctl, unsigned long arg) > { > @@ -1861,6 +1977,14 @@ long kvm_arch_vm_ioctl(struct file *filp, > r = -EFAULT; > break; > } > + case KVM_PPC_GET_CPU_CHAR: { > + struct kvm_ppc_cpu_char cpuchar; > + > + r = kvmppc_get_cpu_char(&cpuchar); > + if (r >= 0 && copy_to_user(argp, &cpuchar, sizeof(cpuchar))) > + r = -EFAULT; > + break; > + } > default: { > struct kvm *kvm = filp->private_data; > r = kvm->arch.kvm_ops->arch_vm_ioctl(filp, ioctl, arg); > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 282d7613..e96e629 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -932,6 +932,7 @@ struct kvm_ppc_resize_hpt { > #define KVM_CAP_HYPERV_SYNIC2 148 > #define KVM_CAP_HYPERV_VP_INDEX 149 > #define KVM_CAP_S390_AIS_MIGRATION 150 > +#define KVM_CAP_PPC_GET_CPU_CHAR 151 > > #ifdef KVM_CAP_IRQ_ROUTING > > @@ -1261,6 +1262,8 @@ struct kvm_s390_ucas_mapping { > #define KVM_PPC_CONFIGURE_V3_MMU _IOW(KVMIO, 0xaf, struct kvm_ppc_mmuv3_cfg) > /* Available with KVM_CAP_PPC_RADIX_MMU */ > #define KVM_PPC_GET_RMMU_INFO _IOW(KVMIO, 0xb0, struct kvm_ppc_rmmu_info) > +/* Available with KVM_CAP_PPC_GET_CPU_CHAR */ > +#define KVM_PPC_GET_CPU_CHAR _IOR(KVMIO, 0xb1, struct kvm_ppc_cpu_char) > > /* ioctl for vm fd */ > #define KVM_CREATE_DEVICE _IOWR(KVMIO, 0xe0, struct kvm_create_device) > Thanks, looks good. Would you like this in 4.15? Paolo
On Tue, Jan 16, 2018 at 03:45:11PM +0100, Paolo Bonzini wrote: > On 16/01/2018 01:59, Paul Mackerras wrote: > > This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace > > information about the underlying machine's level of vulnerability > > to the recently announced vulnerabilities CVE-2017-5715, > > CVE-2017-5753 and CVE-2017-5754, and whether the machine provides > > instructions to assist software to work around the vulnerabilities. > > > > The ioctl returns two u64 words describing characteristics of the > > CPU and required software behaviour respectively, plus two mask > > words which indicate which bits have been filled in by the kernel, > > for extensibility. The bit definitions are the same as for the > > new H_GET_CPU_CHARACTERISTICS hypercall. > > > > There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which > > indicates whether the new ioctl is available. > > > > Signed-off-by: Paul Mackerras <paulus@ozlabs.org> > > --- > > Documentation/virtual/kvm/api.txt | 46 +++++++++++++ > > arch/powerpc/include/uapi/asm/kvm.h | 22 +++++++ > > arch/powerpc/kvm/powerpc.c | 124 ++++++++++++++++++++++++++++++++++++ > > include/uapi/linux/kvm.h | 3 + > > 4 files changed, 195 insertions(+) > > > > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt > > index f670e4b..85ca84a 100644 > > --- a/Documentation/virtual/kvm/api.txt > > +++ b/Documentation/virtual/kvm/api.txt > > @@ -3394,6 +3394,52 @@ invalid, if invalid pages are written to (e.g. after the end of memory) > > or if no page table is present for the addresses (e.g. when using > > hugepages). > > > > +4.108 KVM_PPC_GET_CPU_CHAR > > + > > +Capability: KVM_CAP_PPC_GET_CPU_CHAR > > +Architectures: powerpc > > +Type: vm ioctl > > +Parameters: struct kvm_ppc_cpu_char (out) > > +Returns: 0 on successful completion > > + -EFAULT if struct kvm_ppc_cpu_char cannot be written > > + > > +This ioctl gives userspace information about certain characteristics > > +of the CPU relating to speculative execution of instructions and > > +possible information leakage resulting from speculative execution (see > > +CVE-2017-5715, CVE-2017-5753 and CVE-2017-5754). The information is > > +returned in struct kvm_ppc_cpu_char, which looks like this: > > + > > +struct kvm_ppc_cpu_char { > > + __u64 character; /* characteristics of the CPU */ > > + __u64 behaviour; /* recommended software behaviour */ > > + __u64 character_mask; /* valid bits in character */ > > + __u64 behaviour_mask; /* valid bits in behaviour */ > > +}; > > + > > +For extensibility, the character_mask and behaviour_mask fields > > +indicate which bits of character and behaviour have been filled in by > > +the kernel. If the set of defined bits is extended in future then > > +userspace will be able to tell whether it is running on a kernel that > > +knows about the new bits. > > + > > +The character field describes attributes of the CPU which can help > > +with preventing inadvertent information disclosure - specifically, > > +whether there is an instruction to flash-invalidate the L1 data cache > > +(ori 30,30,0 or mtspr SPRN_TRIG2,rN), whether the L1 data cache is set > > +to a mode where entries can only be used by the thread that created > > +them, whether the bcctr[l] instruction prevents speculation, and > > +whether a speculation barrier instruction (ori 31,31,0) is provided. > > + > > +The behaviour field describes actions that software should take to > > +prevent inadvertent information disclosure, and thus describes which > > +vulnerabilities the hardware is subject to; specifically whether the > > +L1 data cache should be flushed when returning to user mode from the > > +kernel, and whether a speculation barrier should be placed between an > > +array bounds check and the array access. > > + > > +These fields use the same bit definitions as the new > > +H_GET_CPU_CHARACTERISTICS hypercall. > > + > > 5. The kvm_run structure > > ------------------------ > > > > diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h > > index 61d6049..ce74bed 100644 > > --- a/arch/powerpc/include/uapi/asm/kvm.h > > +++ b/arch/powerpc/include/uapi/asm/kvm.h > > @@ -443,6 +443,28 @@ struct kvm_ppc_rmmu_info { > > __u32 ap_encodings[8]; > > }; > > > > +/* For KVM_PPC_GET_CPU_CHAR */ > > +struct kvm_ppc_cpu_char { > > + __u64 character; /* characteristics of the CPU */ > > + __u64 behaviour; /* recommended software behaviour */ > > + __u64 character_mask; /* valid bits in character */ > > + __u64 behaviour_mask; /* valid bits in behaviour */ > > +}; > > + > > +/* > > + * Values for character and character_mask. > > + * These are identical to the values used by H_GET_CPU_CHARACTERISTICS. > > + */ > > +#define KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 (1ULL << 63) > > +#define KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED (1ULL << 62) > > +#define KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 (1ULL << 61) > > +#define KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 (1ULL << 60) > > +#define KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV (1ULL << 59) > > + > > +#define KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY (1ULL << 63) > > +#define KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR (1ULL << 62) > > +#define KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR (1ULL << 61) > > + > > /* Per-vcpu XICS interrupt controller state */ > > #define KVM_REG_PPC_ICP_STATE (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0x8c) > > > > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c > > index 1915e86..c9cecff 100644 > > --- a/arch/powerpc/kvm/powerpc.c > > +++ b/arch/powerpc/kvm/powerpc.c > > @@ -39,6 +39,10 @@ > > #include <asm/iommu.h> > > #include <asm/switch_to.h> > > #include <asm/xive.h> > > +#ifdef CONFIG_PPC_PSERIES > > +#include <asm/hvcall.h> > > +#include <asm/plpar_wrappers.h> > > +#endif > > > > #include "timing.h" > > #include "irq.h" > > @@ -548,6 +552,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > > #ifdef CONFIG_KVM_XICS > > case KVM_CAP_IRQ_XICS: > > #endif > > + case KVM_CAP_PPC_GET_CPU_CHAR: > > r = 1; > > break; > > > > @@ -1759,6 +1764,117 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, > > return r; > > } > > > > +#ifdef CONFIG_PPC_BOOK3S_64 > > +/* > > + * These functions check whether the underlying hardware is safe > > + * against attacks based on observing the effects of speculatively > > + * executed instructions, and whether it supplies instructions for > > + * use in workarounds. The information comes from firmware, either > > + * via the device tree on powernv platforms or from an hcall on > > + * pseries platforms. > > + */ > > +#ifdef CONFIG_PPC_PSERIES > > +static int pseries_get_cpu_char(struct kvm_ppc_cpu_char *cp) > > +{ > > + struct h_cpu_char_result c; > > + unsigned long rc; > > + > > + if (!machine_is(pseries)) > > + return -ENOTTY; > > + > > + rc = plpar_get_cpu_characteristics(&c); > > + if (rc == H_SUCCESS) { > > + cp->character = c.character; > > + cp->behaviour = c.behaviour; > > + cp->character_mask = KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 | > > + KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED | > > + KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 | > > + KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 | > > + KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV; > > + cp->behaviour_mask = KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY | > > + KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR | > > + KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR; > > + } > > + return 0; > > +} > > +#else > > +static int pseries_get_cpu_char(struct kvm_ppc_cpu_char *cp) > > +{ > > + return -ENOTTY; > > +} > > +#endif > > + > > +static inline bool have_fw_feat(struct device_node *fw_features, > > + const char *state, const char *name) > > +{ > > + struct device_node *np; > > + bool r = false; > > + > > + np = of_get_child_by_name(fw_features, name); > > + if (np) { > > + r = of_property_read_bool(np, state); > > + of_node_put(np); > > + } > > + return r; > > +} > > + > > +static int kvmppc_get_cpu_char(struct kvm_ppc_cpu_char *cp) > > +{ > > + struct device_node *np, *fw_features; > > + int r; > > + > > + memset(cp, 0, sizeof(*cp)); > > + r = pseries_get_cpu_char(cp); > > + if (r != -ENOTTY) > > + return r; > > + > > + np = of_find_node_by_name(NULL, "ibm,opal"); > > + if (np) { > > + fw_features = of_get_child_by_name(np, "fw-features"); > > + of_node_put(np); > > + if (!fw_features) > > + return 0; > > + if (have_fw_feat(fw_features, "enabled", > > + "inst-spec-barrier-ori31,31,0")) > > + cp->character |= KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31; > > + if (have_fw_feat(fw_features, "enabled", > > + "fw-bcctrl-serialized")) > > + cp->character |= KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED; > > + if (have_fw_feat(fw_features, "enabled", > > + "inst-l1d-flush-ori30,30,0")) > > + cp->character |= KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30; > > + if (have_fw_feat(fw_features, "enabled", > > + "inst-l1d-flush-trig2")) > > + cp->character |= KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2; > > + if (have_fw_feat(fw_features, "enabled", > > + "fw-l1d-thread-split")) > > + cp->character |= KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV; > > + cp->character_mask = KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 | > > + KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED | > > + KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 | > > + KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 | > > + KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV; > > + > > + if (have_fw_feat(fw_features, "enabled", > > + "speculation-policy-favor-security")) > > + cp->behaviour |= KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY; > > + if (!have_fw_feat(fw_features, "disabled", > > + "needs-l1d-flush-msr-pr-0-to-1")) > > + cp->behaviour |= KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR; > > + if (!have_fw_feat(fw_features, "disabled", > > + "needs-spec-barrier-for-bound-checks")) > > + cp->behaviour |= KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR; > > + cp->behaviour_mask = KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY | > > + KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR | > > + KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR; > > + > > + of_node_put(fw_features); > > + } > > + > > + return 0; > > +} > > +#endif > > + > > long kvm_arch_vm_ioctl(struct file *filp, > > unsigned int ioctl, unsigned long arg) > > { > > @@ -1861,6 +1977,14 @@ long kvm_arch_vm_ioctl(struct file *filp, > > r = -EFAULT; > > break; > > } > > + case KVM_PPC_GET_CPU_CHAR: { > > + struct kvm_ppc_cpu_char cpuchar; > > + > > + r = kvmppc_get_cpu_char(&cpuchar); > > + if (r >= 0 && copy_to_user(argp, &cpuchar, sizeof(cpuchar))) > > + r = -EFAULT; > > + break; > > + } > > default: { > > struct kvm *kvm = filp->private_data; > > r = kvm->arch.kvm_ops->arch_vm_ioctl(filp, ioctl, arg); > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > > index 282d7613..e96e629 100644 > > --- a/include/uapi/linux/kvm.h > > +++ b/include/uapi/linux/kvm.h > > @@ -932,6 +932,7 @@ struct kvm_ppc_resize_hpt { > > #define KVM_CAP_HYPERV_SYNIC2 148 > > #define KVM_CAP_HYPERV_VP_INDEX 149 > > #define KVM_CAP_S390_AIS_MIGRATION 150 > > +#define KVM_CAP_PPC_GET_CPU_CHAR 151 > > > > #ifdef KVM_CAP_IRQ_ROUTING > > > > @@ -1261,6 +1262,8 @@ struct kvm_s390_ucas_mapping { > > #define KVM_PPC_CONFIGURE_V3_MMU _IOW(KVMIO, 0xaf, struct kvm_ppc_mmuv3_cfg) > > /* Available with KVM_CAP_PPC_RADIX_MMU */ > > #define KVM_PPC_GET_RMMU_INFO _IOW(KVMIO, 0xb0, struct kvm_ppc_rmmu_info) > > +/* Available with KVM_CAP_PPC_GET_CPU_CHAR */ > > +#define KVM_PPC_GET_CPU_CHAR _IOR(KVMIO, 0xb1, struct kvm_ppc_cpu_char) > > > > /* ioctl for vm fd */ > > #define KVM_CREATE_DEVICE _IOWR(KVMIO, 0xe0, struct kvm_create_device) > > > > Thanks, looks good. Would you like this in 4.15? Yes please. Will you just apply the patch, or do you want me to put it in a branch for you to pull? The patch depends on 191eccb15809 ("powerpc/pseries: Add H_GET_CPU_CHARACTERISTICS flags & wrapper", 2018-01-09) which is in Linus' tree as of v4.15-rc8, and I see that the kvm master branch is at rc8, so it should apply on the master branch just fine. Thanks, Paul.
2018-01-17 08:51+1100, Paul Mackerras: > On Tue, Jan 16, 2018 at 03:45:11PM +0100, Paolo Bonzini wrote: > > On 16/01/2018 01:59, Paul Mackerras wrote: > > > This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace > > > information about the underlying machine's level of vulnerability > > > to the recently announced vulnerabilities CVE-2017-5715, > > > CVE-2017-5753 and CVE-2017-5754, and whether the machine provides > > > instructions to assist software to work around the vulnerabilities. > > > > > > The ioctl returns two u64 words describing characteristics of the > > > CPU and required software behaviour respectively, plus two mask > > > words which indicate which bits have been filled in by the kernel, > > > for extensibility. The bit definitions are the same as for the > > > new H_GET_CPU_CHARACTERISTICS hypercall. > > > > > > There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which > > > indicates whether the new ioctl is available. > > > > > > Signed-off-by: Paul Mackerras <paulus@ozlabs.org> > > > --- > > > > Thanks, looks good. Would you like this in 4.15? > > Yes please. Will you just apply the patch, or do you want me to put > it in a branch for you to pull? I can apply it directly. Do I understand correctly that the interface is a KVM hypercall because we need to forward this information into guests and other userspace can do nothing with the information? Thanks.
On 17/01/2018 15:27, Radim Krčmář wrote: > 2018-01-17 08:51+1100, Paul Mackerras: >> On Tue, Jan 16, 2018 at 03:45:11PM +0100, Paolo Bonzini wrote: >>> On 16/01/2018 01:59, Paul Mackerras wrote: >>>> This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace >>>> information about the underlying machine's level of vulnerability >>>> to the recently announced vulnerabilities CVE-2017-5715, >>>> CVE-2017-5753 and CVE-2017-5754, and whether the machine provides >>>> instructions to assist software to work around the vulnerabilities. >>>> >>>> The ioctl returns two u64 words describing characteristics of the >>>> CPU and required software behaviour respectively, plus two mask >>>> words which indicate which bits have been filled in by the kernel, >>>> for extensibility. The bit definitions are the same as for the >>>> new H_GET_CPU_CHARACTERISTICS hypercall. >>>> >>>> There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which >>>> indicates whether the new ioctl is available. >>>> >>>> Signed-off-by: Paul Mackerras <paulus@ozlabs.org> >>>> --- >>> >>> Thanks, looks good. Would you like this in 4.15? >> >> Yes please. Will you just apply the patch, or do you want me to put >> it in a branch for you to pull? > > I can apply it directly. > > Do I understand correctly that the interface is a KVM hypercall because ^^^^^^^^^ ioctl? > we need to forward this information into guests and other userspace can > do nothing with the information? There will probably be someone else that can consume it sooner or later. sysfs or /proc/cpuinfo probably would be a better interface. But I guess KVM is the prime consumer... Paolo
On Wed, Jan 17, 2018 at 07:03:13PM +0100, Paolo Bonzini wrote: > On 17/01/2018 15:27, Radim Krčmář wrote: > > 2018-01-17 08:51+1100, Paul Mackerras: > >> On Tue, Jan 16, 2018 at 03:45:11PM +0100, Paolo Bonzini wrote: > >>> On 16/01/2018 01:59, Paul Mackerras wrote: > >>>> This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace > >>>> information about the underlying machine's level of vulnerability > >>>> to the recently announced vulnerabilities CVE-2017-5715, > >>>> CVE-2017-5753 and CVE-2017-5754, and whether the machine provides > >>>> instructions to assist software to work around the vulnerabilities. > >>>> > >>>> The ioctl returns two u64 words describing characteristics of the > >>>> CPU and required software behaviour respectively, plus two mask > >>>> words which indicate which bits have been filled in by the kernel, > >>>> for extensibility. The bit definitions are the same as for the > >>>> new H_GET_CPU_CHARACTERISTICS hypercall. > >>>> > >>>> There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which > >>>> indicates whether the new ioctl is available. > >>>> > >>>> Signed-off-by: Paul Mackerras <paulus@ozlabs.org> > >>>> --- > >>> > >>> Thanks, looks good. Would you like this in 4.15? > >> > >> Yes please. Will you just apply the patch, or do you want me to put > >> it in a branch for you to pull? > > > > I can apply it directly. > > > > Do I understand correctly that the interface is a KVM hypercall because > ^^^^^^^^^ > > ioctl? > > > we need to forward this information into guests and other userspace can > > do nothing with the information? > > There will probably be someone else that can consume it sooner or later. > sysfs or /proc/cpuinfo probably would be a better interface. But I > guess KVM is the prime consumer... Right, it is. KVM needs all the bits, and I don't see why any other userspace consumer would need more than a couple of them. Paul.
On Wed, Jan 17, 2018 at 07:03:13PM +0100, Paolo Bonzini wrote: > On 17/01/2018 15:27, Radim Krčmář wrote: > > 2018-01-17 08:51+1100, Paul Mackerras: > >> On Tue, Jan 16, 2018 at 03:45:11PM +0100, Paolo Bonzini wrote: > >>> On 16/01/2018 01:59, Paul Mackerras wrote: > >>>> This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace > >>>> information about the underlying machine's level of vulnerability > >>>> to the recently announced vulnerabilities CVE-2017-5715, > >>>> CVE-2017-5753 and CVE-2017-5754, and whether the machine provides > >>>> instructions to assist software to work around the vulnerabilities. > >>>> > >>>> The ioctl returns two u64 words describing characteristics of the > >>>> CPU and required software behaviour respectively, plus two mask > >>>> words which indicate which bits have been filled in by the kernel, > >>>> for extensibility. The bit definitions are the same as for the > >>>> new H_GET_CPU_CHARACTERISTICS hypercall. > >>>> > >>>> There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which > >>>> indicates whether the new ioctl is available. > >>>> > >>>> Signed-off-by: Paul Mackerras <paulus@ozlabs.org> > >>>> --- > >>> > >>> Thanks, looks good. Would you like this in 4.15? > >> > >> Yes please. Will you just apply the patch, or do you want me to put > >> it in a branch for you to pull? > > > > I can apply it directly. > > > > Do I understand correctly that the interface is a KVM hypercall because > ^^^^^^^^^ > > ioctl? > > > we need to forward this information into guests and other userspace can > > do nothing with the information? > > There will probably be someone else that can consume it sooner or later. > sysfs or /proc/cpuinfo probably would be a better interface. But I > guess KVM is the prime consumer... Even if we have a more general interface, I think we'll still want a KVM specific one (even if it just draws the info from the general one). It's conceivable that there could be complications which make one of these things behave different from the PoV of a guest than from the PoV of a regular userspace program. For that reason, I think it's best for qemu to draw this information from KVM for passing to guests, even if there is a different source that most userspace programs will use.
On Wed, Jan 17, 2018 at 03:27:11PM +0100, Radim Krčmář wrote: > 2018-01-17 08:51+1100, Paul Mackerras: > > On Tue, Jan 16, 2018 at 03:45:11PM +0100, Paolo Bonzini wrote: > > > On 16/01/2018 01:59, Paul Mackerras wrote: > > > > This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace > > > > information about the underlying machine's level of vulnerability > > > > to the recently announced vulnerabilities CVE-2017-5715, > > > > CVE-2017-5753 and CVE-2017-5754, and whether the machine provides > > > > instructions to assist software to work around the vulnerabilities. > > > > > > > > The ioctl returns two u64 words describing characteristics of the > > > > CPU and required software behaviour respectively, plus two mask > > > > words which indicate which bits have been filled in by the kernel, > > > > for extensibility. The bit definitions are the same as for the > > > > new H_GET_CPU_CHARACTERISTICS hypercall. > > > > > > > > There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which > > > > indicates whether the new ioctl is available. > > > > > > > > Signed-off-by: Paul Mackerras <paulus@ozlabs.org> > > > > --- > > > > > > Thanks, looks good. Would you like this in 4.15? > > > > Yes please. Will you just apply the patch, or do you want me to put > > it in a branch for you to pull? > > I can apply it directly. Can you please do so ASAP; we have a whole raft of bugs downstream waiting on this. > Do I understand correctly that the interface is a KVM hypercall because > we need to forward this information into guests and other userspace can > do nothing with the information?
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index f670e4b..85ca84a 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3394,6 +3394,52 @@ invalid, if invalid pages are written to (e.g. after the end of memory) or if no page table is present for the addresses (e.g. when using hugepages). +4.108 KVM_PPC_GET_CPU_CHAR + +Capability: KVM_CAP_PPC_GET_CPU_CHAR +Architectures: powerpc +Type: vm ioctl +Parameters: struct kvm_ppc_cpu_char (out) +Returns: 0 on successful completion + -EFAULT if struct kvm_ppc_cpu_char cannot be written + +This ioctl gives userspace information about certain characteristics +of the CPU relating to speculative execution of instructions and +possible information leakage resulting from speculative execution (see +CVE-2017-5715, CVE-2017-5753 and CVE-2017-5754). The information is +returned in struct kvm_ppc_cpu_char, which looks like this: + +struct kvm_ppc_cpu_char { + __u64 character; /* characteristics of the CPU */ + __u64 behaviour; /* recommended software behaviour */ + __u64 character_mask; /* valid bits in character */ + __u64 behaviour_mask; /* valid bits in behaviour */ +}; + +For extensibility, the character_mask and behaviour_mask fields +indicate which bits of character and behaviour have been filled in by +the kernel. If the set of defined bits is extended in future then +userspace will be able to tell whether it is running on a kernel that +knows about the new bits. + +The character field describes attributes of the CPU which can help +with preventing inadvertent information disclosure - specifically, +whether there is an instruction to flash-invalidate the L1 data cache +(ori 30,30,0 or mtspr SPRN_TRIG2,rN), whether the L1 data cache is set +to a mode where entries can only be used by the thread that created +them, whether the bcctr[l] instruction prevents speculation, and +whether a speculation barrier instruction (ori 31,31,0) is provided. + +The behaviour field describes actions that software should take to +prevent inadvertent information disclosure, and thus describes which +vulnerabilities the hardware is subject to; specifically whether the +L1 data cache should be flushed when returning to user mode from the +kernel, and whether a speculation barrier should be placed between an +array bounds check and the array access. + +These fields use the same bit definitions as the new +H_GET_CPU_CHARACTERISTICS hypercall. + 5. The kvm_run structure ------------------------ diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h index 61d6049..ce74bed 100644 --- a/arch/powerpc/include/uapi/asm/kvm.h +++ b/arch/powerpc/include/uapi/asm/kvm.h @@ -443,6 +443,28 @@ struct kvm_ppc_rmmu_info { __u32 ap_encodings[8]; }; +/* For KVM_PPC_GET_CPU_CHAR */ +struct kvm_ppc_cpu_char { + __u64 character; /* characteristics of the CPU */ + __u64 behaviour; /* recommended software behaviour */ + __u64 character_mask; /* valid bits in character */ + __u64 behaviour_mask; /* valid bits in behaviour */ +}; + +/* + * Values for character and character_mask. + * These are identical to the values used by H_GET_CPU_CHARACTERISTICS. + */ +#define KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 (1ULL << 63) +#define KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED (1ULL << 62) +#define KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 (1ULL << 61) +#define KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 (1ULL << 60) +#define KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV (1ULL << 59) + +#define KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY (1ULL << 63) +#define KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR (1ULL << 62) +#define KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR (1ULL << 61) + /* Per-vcpu XICS interrupt controller state */ #define KVM_REG_PPC_ICP_STATE (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0x8c) diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index 1915e86..c9cecff 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -39,6 +39,10 @@ #include <asm/iommu.h> #include <asm/switch_to.h> #include <asm/xive.h> +#ifdef CONFIG_PPC_PSERIES +#include <asm/hvcall.h> +#include <asm/plpar_wrappers.h> +#endif #include "timing.h" #include "irq.h" @@ -548,6 +552,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) #ifdef CONFIG_KVM_XICS case KVM_CAP_IRQ_XICS: #endif + case KVM_CAP_PPC_GET_CPU_CHAR: r = 1; break; @@ -1759,6 +1764,117 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, return r; } +#ifdef CONFIG_PPC_BOOK3S_64 +/* + * These functions check whether the underlying hardware is safe + * against attacks based on observing the effects of speculatively + * executed instructions, and whether it supplies instructions for + * use in workarounds. The information comes from firmware, either + * via the device tree on powernv platforms or from an hcall on + * pseries platforms. + */ +#ifdef CONFIG_PPC_PSERIES +static int pseries_get_cpu_char(struct kvm_ppc_cpu_char *cp) +{ + struct h_cpu_char_result c; + unsigned long rc; + + if (!machine_is(pseries)) + return -ENOTTY; + + rc = plpar_get_cpu_characteristics(&c); + if (rc == H_SUCCESS) { + cp->character = c.character; + cp->behaviour = c.behaviour; + cp->character_mask = KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 | + KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED | + KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 | + KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 | + KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV; + cp->behaviour_mask = KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY | + KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR | + KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR; + } + return 0; +} +#else +static int pseries_get_cpu_char(struct kvm_ppc_cpu_char *cp) +{ + return -ENOTTY; +} +#endif + +static inline bool have_fw_feat(struct device_node *fw_features, + const char *state, const char *name) +{ + struct device_node *np; + bool r = false; + + np = of_get_child_by_name(fw_features, name); + if (np) { + r = of_property_read_bool(np, state); + of_node_put(np); + } + return r; +} + +static int kvmppc_get_cpu_char(struct kvm_ppc_cpu_char *cp) +{ + struct device_node *np, *fw_features; + int r; + + memset(cp, 0, sizeof(*cp)); + r = pseries_get_cpu_char(cp); + if (r != -ENOTTY) + return r; + + np = of_find_node_by_name(NULL, "ibm,opal"); + if (np) { + fw_features = of_get_child_by_name(np, "fw-features"); + of_node_put(np); + if (!fw_features) + return 0; + if (have_fw_feat(fw_features, "enabled", + "inst-spec-barrier-ori31,31,0")) + cp->character |= KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31; + if (have_fw_feat(fw_features, "enabled", + "fw-bcctrl-serialized")) + cp->character |= KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED; + if (have_fw_feat(fw_features, "enabled", + "inst-l1d-flush-ori30,30,0")) + cp->character |= KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30; + if (have_fw_feat(fw_features, "enabled", + "inst-l1d-flush-trig2")) + cp->character |= KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2; + if (have_fw_feat(fw_features, "enabled", + "fw-l1d-thread-split")) + cp->character |= KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV; + cp->character_mask = KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 | + KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED | + KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 | + KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 | + KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV; + + if (have_fw_feat(fw_features, "enabled", + "speculation-policy-favor-security")) + cp->behaviour |= KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY; + if (!have_fw_feat(fw_features, "disabled", + "needs-l1d-flush-msr-pr-0-to-1")) + cp->behaviour |= KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR; + if (!have_fw_feat(fw_features, "disabled", + "needs-spec-barrier-for-bound-checks")) + cp->behaviour |= KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR; + cp->behaviour_mask = KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY | + KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR | + KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR; + + of_node_put(fw_features); + } + + return 0; +} +#endif + long kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { @@ -1861,6 +1977,14 @@ long kvm_arch_vm_ioctl(struct file *filp, r = -EFAULT; break; } + case KVM_PPC_GET_CPU_CHAR: { + struct kvm_ppc_cpu_char cpuchar; + + r = kvmppc_get_cpu_char(&cpuchar); + if (r >= 0 && copy_to_user(argp, &cpuchar, sizeof(cpuchar))) + r = -EFAULT; + break; + } default: { struct kvm *kvm = filp->private_data; r = kvm->arch.kvm_ops->arch_vm_ioctl(filp, ioctl, arg); diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 282d7613..e96e629 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -932,6 +932,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_HYPERV_SYNIC2 148 #define KVM_CAP_HYPERV_VP_INDEX 149 #define KVM_CAP_S390_AIS_MIGRATION 150 +#define KVM_CAP_PPC_GET_CPU_CHAR 151 #ifdef KVM_CAP_IRQ_ROUTING @@ -1261,6 +1262,8 @@ struct kvm_s390_ucas_mapping { #define KVM_PPC_CONFIGURE_V3_MMU _IOW(KVMIO, 0xaf, struct kvm_ppc_mmuv3_cfg) /* Available with KVM_CAP_PPC_RADIX_MMU */ #define KVM_PPC_GET_RMMU_INFO _IOW(KVMIO, 0xb0, struct kvm_ppc_rmmu_info) +/* Available with KVM_CAP_PPC_GET_CPU_CHAR */ +#define KVM_PPC_GET_CPU_CHAR _IOR(KVMIO, 0xb1, struct kvm_ppc_cpu_char) /* ioctl for vm fd */ #define KVM_CREATE_DEVICE _IOWR(KVMIO, 0xe0, struct kvm_create_device)
This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace information about the underlying machine's level of vulnerability to the recently announced vulnerabilities CVE-2017-5715, CVE-2017-5753 and CVE-2017-5754, and whether the machine provides instructions to assist software to work around the vulnerabilities. The ioctl returns two u64 words describing characteristics of the CPU and required software behaviour respectively, plus two mask words which indicate which bits have been filled in by the kernel, for extensibility. The bit definitions are the same as for the new H_GET_CPU_CHARACTERISTICS hypercall. There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which indicates whether the new ioctl is available. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> --- Documentation/virtual/kvm/api.txt | 46 +++++++++++++ arch/powerpc/include/uapi/asm/kvm.h | 22 +++++++ arch/powerpc/kvm/powerpc.c | 124 ++++++++++++++++++++++++++++++++++++ include/uapi/linux/kvm.h | 3 + 4 files changed, 195 insertions(+)