| Message ID | 20230220183847.59159-35-michael.roth@amd.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support | expand |
On Mon, 20 Feb 2023 12:38:25 -0600 Michael Roth <michael.roth@amd.com> wrote: > From: Brijesh Singh <brijesh.singh@amd.com> > > KVM_SEV_SNP_LAUNCH_START begins the launch process for an SEV-SNP guest. > The command initializes a cryptographic digest context used to construct > the measurement of the guest. If the guest is expected to be migrated, > the command also binds a migration agent (MA) to the guest. > > For more information see the SEV-SNP specification. > > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > Signed-off-by: Michael Roth <michael.roth@amd.com> > --- > .../virt/kvm/x86/amd-memory-encryption.rst | 24 ++++ > arch/x86/kvm/svm/sev.c | 121 +++++++++++++++++- > arch/x86/kvm/svm/svm.h | 1 + > include/uapi/linux/kvm.h | 10 ++ > 4 files changed, 153 insertions(+), 3 deletions(-) > > diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst > index 2432213bd0ea..58971fc02a15 100644 > --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst > +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst > @@ -461,6 +461,30 @@ The flags bitmap is defined as:: > If the specified flags is not supported then return -EOPNOTSUPP, and the supported > flags are returned. > > +19. KVM_SNP_LAUNCH_START > +------------------------ > + > +The KVM_SNP_LAUNCH_START command is used for creating the memory encryption > +context for the SEV-SNP guest. To create the encryption context, user must > +provide a guest policy, migration agent (if any) and guest OS visible > +workarounds value as defined SEV-SNP specification. > + > +Parameters (in): struct kvm_snp_launch_start > + > +Returns: 0 on success, -negative on error > + > +:: > + > + struct kvm_sev_snp_launch_start { > + __u64 policy; /* Guest policy to use. */ > + __u64 ma_uaddr; /* userspace address of migration agent */ > + __u8 ma_en; /* 1 if the migration agent is enabled */ > + __u8 imi_en; /* set IMI to 1. */ > + __u8 gosvw[16]; /* guest OS visible workarounds */ > + }; > + > +See the SEV-SNP specification for further detail on the launch input. > + > References > ========== > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index a8efe1f6bf77..097bb2138360 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -22,6 +22,7 @@ > #include <asm/pkru.h> > #include <asm/trapnr.h> > #include <asm/fpu/xcr.h> > +#include <asm/sev.h> > > #include "mmu.h" > #include "x86.h" > @@ -75,6 +76,8 @@ static unsigned int nr_asids; > static unsigned long *sev_asid_bitmap; > static unsigned long *sev_reclaim_asid_bitmap; > > +static int snp_decommission_context(struct kvm *kvm); > + > struct enc_region { > struct list_head list; > unsigned long npages; > @@ -100,12 +103,17 @@ static int sev_flush_asids(int min_asid, int max_asid) > down_write(&sev_deactivate_lock); > > wbinvd_on_all_cpus(); > - ret = sev_guest_df_flush(&error); > + > + if (sev_snp_enabled) > + ret = sev_do_cmd(SEV_CMD_SNP_DF_FLUSH, NULL, &error); > + else > + ret = sev_guest_df_flush(&error); > > up_write(&sev_deactivate_lock); > > if (ret) > - pr_err("SEV: DF_FLUSH failed, ret=%d, error=%#x\n", ret, error); > + pr_err("SEV%s: DF_FLUSH failed, ret=%d, error=%#x\n", > + sev_snp_enabled ? "-SNP" : "", ret, error); > > return ret; > } > @@ -2011,6 +2019,80 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd) > return ret; > } > > +/* > + * The guest context contains all the information, keys and metadata > + * associated with the guest that the firmware tracks to implement SEV > + * and SNP features. The firmware stores the guest context in hypervisor > + * provide page via the SNP_GCTX_CREATE command. > + */ > +static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp) > +{ > + struct sev_data_snp_addr data = {}; > + void *context; > + int rc; > + > + /* Allocate memory for context page */ > + context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT); > + if (!context) > + return NULL; > + > + data.gctx_paddr = __psp_pa(context); > + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_GCTX_CREATE, &data, &argp->error); > + if (rc) { > + snp_free_firmware_page(context); > + return NULL; > + } > + > + return context; > +} > + > +static int snp_bind_asid(struct kvm *kvm, int *error) > +{ > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > + struct sev_data_snp_activate data = {0}; > + > + data.gctx_paddr = __psp_pa(sev->snp_context); > + data.asid = sev_get_asid(kvm); > + return sev_issue_cmd(kvm, SEV_CMD_SNP_ACTIVATE, &data, error); According to the SNP ABI specification[1] 8.10 SNP_ACTIVATE: "The firmware checks that a DF_FLUSH is not required. If a DF_FLUSH is required, the firmware returns DFFLUSH_REQUIRED. Note that all ASIDs are marked to require a DF_FLUSH at reset." Do we need a SNP_DF_FLUSH here before calling SNP_ACTIVATE or handle the situation if the PSP firmware returns DFFLUSH_REQUIRED? [1] https://www.amd.com/system/files/TechDocs/56860.pdf > +} > + > +static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) > +{ > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > + struct sev_data_snp_launch_start start = {0}; > + struct kvm_sev_snp_launch_start params; > + int rc; > + > + if (!sev_snp_guest(kvm)) > + return -ENOTTY; > + > + if (copy_from_user(¶ms, (void __user *)(uintptr_t)argp->data, sizeof(params))) > + return -EFAULT; > + > + sev->snp_context = snp_context_create(kvm, argp); > + if (!sev->snp_context) > + return -ENOTTY; > + > + start.gctx_paddr = __psp_pa(sev->snp_context); > + start.policy = params.policy; > + memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw)); > + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error); > + if (rc) > + goto e_free_context; > + > + sev->fd = argp->sev_fd; > + rc = snp_bind_asid(kvm, &argp->error); > + if (rc) > + goto e_free_context; > + > + return 0; > + > +e_free_context: > + snp_decommission_context(kvm); > + > + return rc; > +} > + > int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp) > { > struct kvm_sev_cmd sev_cmd; > @@ -2101,6 +2183,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp) > case KVM_SEV_RECEIVE_FINISH: > r = sev_receive_finish(kvm, &sev_cmd); > break; > + case KVM_SEV_SNP_LAUNCH_START: > + r = snp_launch_start(kvm, &sev_cmd); > + break; > default: > r = -EINVAL; > goto out; > @@ -2292,6 +2377,28 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd) > return ret; > } > > +static int snp_decommission_context(struct kvm *kvm) > +{ > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > + struct sev_data_snp_addr data = {}; > + int ret; > + > + /* If context is not created then do nothing */ > + if (!sev->snp_context) > + return 0; > + > + data.gctx_paddr = __sme_pa(sev->snp_context); > + ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL); > + if (WARN_ONCE(ret, "failed to release guest context")) > + return ret; > + > + /* free the context page now */ > + snp_free_firmware_page(sev->snp_context); > + sev->snp_context = NULL; > + > + return 0; > +} > + > void sev_vm_destroy(struct kvm *kvm) > { > struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > @@ -2333,7 +2440,15 @@ void sev_vm_destroy(struct kvm *kvm) > } > } > > - sev_unbind_asid(kvm, sev->handle); > + if (sev_snp_guest(kvm)) { > + if (snp_decommission_context(kvm)) { > + WARN_ONCE(1, "Failed to free SNP guest context, leaking asid!\n"); > + return; > + } > + } else { > + sev_unbind_asid(kvm, sev->handle); > + } > + > sev_asid_free(sev); > } > > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index 56a5c96d8a36..740969b57425 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -92,6 +92,7 @@ struct kvm_sev_info { > struct misc_cg *misc_cg; /* For misc cgroup accounting */ > atomic_t migration_in_progress; > u64 snp_init_flags; > + void *snp_context; /* SNP guest context page */ > }; > > struct kvm_svm { > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 499cc323f793..cf19799ca5ce 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -1919,6 +1919,7 @@ enum sev_cmd_id { > > /* SNP specific commands */ > KVM_SEV_SNP_INIT, > + KVM_SEV_SNP_LAUNCH_START, > > KVM_SEV_NR_MAX, > }; > @@ -2026,6 +2027,15 @@ struct kvm_snp_init { > __u64 flags; > }; > > +struct kvm_sev_snp_launch_start { > + __u64 policy; > + __u64 ma_uaddr; > + __u8 ma_en; > + __u8 imi_en; > + __u8 gosvw[16]; > + __u8 pad[6]; > +}; > + > #define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0) > #define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1) > #define KVM_DEV_ASSIGN_MASK_INTX (1 << 2)
On 2/23/23 15:41, Zhi Wang wrote: > On Mon, 20 Feb 2023 12:38:25 -0600 > Michael Roth <michael.roth@amd.com> wrote: > >> From: Brijesh Singh <brijesh.singh@amd.com> >> >> KVM_SEV_SNP_LAUNCH_START begins the launch process for an SEV-SNP guest. >> The command initializes a cryptographic digest context used to construct >> the measurement of the guest. If the guest is expected to be migrated, >> the command also binds a migration agent (MA) to the guest. >> >> For more information see the SEV-SNP specification. >> >> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> >> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> >> Signed-off-by: Michael Roth <michael.roth@amd.com> >> --- >> .../virt/kvm/x86/amd-memory-encryption.rst | 24 ++++ >> arch/x86/kvm/svm/sev.c | 121 +++++++++++++++++- >> arch/x86/kvm/svm/svm.h | 1 + >> include/uapi/linux/kvm.h | 10 ++ >> 4 files changed, 153 insertions(+), 3 deletions(-) >> >> diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst >> index 2432213bd0ea..58971fc02a15 100644 >> --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst >> +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst >> @@ -461,6 +461,30 @@ The flags bitmap is defined as:: >> If the specified flags is not supported then return -EOPNOTSUPP, and the supported >> flags are returned. >> >> +19. KVM_SNP_LAUNCH_START >> +------------------------ >> + >> +The KVM_SNP_LAUNCH_START command is used for creating the memory encryption >> +context for the SEV-SNP guest. To create the encryption context, user must >> +provide a guest policy, migration agent (if any) and guest OS visible >> +workarounds value as defined SEV-SNP specification. >> + >> +Parameters (in): struct kvm_snp_launch_start >> + >> +Returns: 0 on success, -negative on error >> + >> +:: >> + >> + struct kvm_sev_snp_launch_start { >> + __u64 policy; /* Guest policy to use. */ >> + __u64 ma_uaddr; /* userspace address of migration agent */ >> + __u8 ma_en; /* 1 if the migration agent is enabled */ >> + __u8 imi_en; /* set IMI to 1. */ >> + __u8 gosvw[16]; /* guest OS visible workarounds */ >> + }; >> + >> +See the SEV-SNP specification for further detail on the launch input. >> + >> References >> ========== >> >> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c >> index a8efe1f6bf77..097bb2138360 100644 >> --- a/arch/x86/kvm/svm/sev.c >> +++ b/arch/x86/kvm/svm/sev.c >> @@ -22,6 +22,7 @@ >> #include <asm/pkru.h> >> #include <asm/trapnr.h> >> #include <asm/fpu/xcr.h> >> +#include <asm/sev.h> >> >> #include "mmu.h" >> #include "x86.h" >> @@ -75,6 +76,8 @@ static unsigned int nr_asids; >> static unsigned long *sev_asid_bitmap; >> static unsigned long *sev_reclaim_asid_bitmap; >> >> +static int snp_decommission_context(struct kvm *kvm); >> + >> struct enc_region { >> struct list_head list; >> unsigned long npages; >> @@ -100,12 +103,17 @@ static int sev_flush_asids(int min_asid, int max_asid) >> down_write(&sev_deactivate_lock); >> >> wbinvd_on_all_cpus(); >> - ret = sev_guest_df_flush(&error); >> + >> + if (sev_snp_enabled) >> + ret = sev_do_cmd(SEV_CMD_SNP_DF_FLUSH, NULL, &error); >> + else >> + ret = sev_guest_df_flush(&error); >> >> up_write(&sev_deactivate_lock); >> >> if (ret) >> - pr_err("SEV: DF_FLUSH failed, ret=%d, error=%#x\n", ret, error); >> + pr_err("SEV%s: DF_FLUSH failed, ret=%d, error=%#x\n", >> + sev_snp_enabled ? "-SNP" : "", ret, error); >> >> return ret; >> } >> @@ -2011,6 +2019,80 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd) >> return ret; >> } >> >> +/* >> + * The guest context contains all the information, keys and metadata >> + * associated with the guest that the firmware tracks to implement SEV >> + * and SNP features. The firmware stores the guest context in hypervisor >> + * provide page via the SNP_GCTX_CREATE command. >> + */ >> +static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp) >> +{ >> + struct sev_data_snp_addr data = {}; >> + void *context; >> + int rc; >> + >> + /* Allocate memory for context page */ >> + context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT); >> + if (!context) >> + return NULL; >> + >> + data.gctx_paddr = __psp_pa(context); >> + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_GCTX_CREATE, &data, &argp->error); >> + if (rc) { >> + snp_free_firmware_page(context); >> + return NULL; >> + } >> + >> + return context; >> +} >> + >> +static int snp_bind_asid(struct kvm *kvm, int *error) >> +{ >> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >> + struct sev_data_snp_activate data = {0}; >> + >> + data.gctx_paddr = __psp_pa(sev->snp_context); >> + data.asid = sev_get_asid(kvm); >> + return sev_issue_cmd(kvm, SEV_CMD_SNP_ACTIVATE, &data, error); > > According to the SNP ABI specification[1] 8.10 SNP_ACTIVATE: > > "The firmware checks that a DF_FLUSH is not required. If a DF_FLUSH is > required, the firmware returns DFFLUSH_REQUIRED. Note that all ASIDs are > marked to require a DF_FLUSH at reset." > > Do we need a SNP_DF_FLUSH here before calling SNP_ACTIVATE or handle the > situation if the PSP firmware returns DFFLUSH_REQUIRED? > > [1] https://www.amd.com/system/files/TechDocs/56860.pdf This is related to ASID use. An initial DF_FLUSH is done which allows any SNP ASID to be used once without requiring a DF_FLUSH. Once an ASID has been used, it cannot be re-used until a DF_FLUSH is performed. The ASID recycling code takes care of that. Thanks, Tom > >> +} >> + >> +static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) >> +{ >> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >> + struct sev_data_snp_launch_start start = {0}; >> + struct kvm_sev_snp_launch_start params; >> + int rc; >> + >> + if (!sev_snp_guest(kvm)) >> + return -ENOTTY; >> + >> + if (copy_from_user(¶ms, (void __user *)(uintptr_t)argp->data, sizeof(params))) >> + return -EFAULT; >> + >> + sev->snp_context = snp_context_create(kvm, argp); >> + if (!sev->snp_context) >> + return -ENOTTY; >> + >> + start.gctx_paddr = __psp_pa(sev->snp_context); >> + start.policy = params.policy; >> + memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw)); >> + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error); >> + if (rc) >> + goto e_free_context; >> + >> + sev->fd = argp->sev_fd; >> + rc = snp_bind_asid(kvm, &argp->error); >> + if (rc) >> + goto e_free_context; >> + >> + return 0; >> + >> +e_free_context: >> + snp_decommission_context(kvm); >> + >> + return rc; >> +} >> + >> int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp) >> { >> struct kvm_sev_cmd sev_cmd; >> @@ -2101,6 +2183,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp) >> case KVM_SEV_RECEIVE_FINISH: >> r = sev_receive_finish(kvm, &sev_cmd); >> break; >> + case KVM_SEV_SNP_LAUNCH_START: >> + r = snp_launch_start(kvm, &sev_cmd); >> + break; >> default: >> r = -EINVAL; >> goto out; >> @@ -2292,6 +2377,28 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd) >> return ret; >> } >> >> +static int snp_decommission_context(struct kvm *kvm) >> +{ >> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >> + struct sev_data_snp_addr data = {}; >> + int ret; >> + >> + /* If context is not created then do nothing */ >> + if (!sev->snp_context) >> + return 0; >> + >> + data.gctx_paddr = __sme_pa(sev->snp_context); >> + ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL); >> + if (WARN_ONCE(ret, "failed to release guest context")) >> + return ret; >> + >> + /* free the context page now */ >> + snp_free_firmware_page(sev->snp_context); >> + sev->snp_context = NULL; >> + >> + return 0; >> +} >> + >> void sev_vm_destroy(struct kvm *kvm) >> { >> struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >> @@ -2333,7 +2440,15 @@ void sev_vm_destroy(struct kvm *kvm) >> } >> } >> >> - sev_unbind_asid(kvm, sev->handle); >> + if (sev_snp_guest(kvm)) { >> + if (snp_decommission_context(kvm)) { >> + WARN_ONCE(1, "Failed to free SNP guest context, leaking asid!\n"); >> + return; >> + } >> + } else { >> + sev_unbind_asid(kvm, sev->handle); >> + } >> + >> sev_asid_free(sev); >> } >> >> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h >> index 56a5c96d8a36..740969b57425 100644 >> --- a/arch/x86/kvm/svm/svm.h >> +++ b/arch/x86/kvm/svm/svm.h >> @@ -92,6 +92,7 @@ struct kvm_sev_info { >> struct misc_cg *misc_cg; /* For misc cgroup accounting */ >> atomic_t migration_in_progress; >> u64 snp_init_flags; >> + void *snp_context; /* SNP guest context page */ >> }; >> >> struct kvm_svm { >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h >> index 499cc323f793..cf19799ca5ce 100644 >> --- a/include/uapi/linux/kvm.h >> +++ b/include/uapi/linux/kvm.h >> @@ -1919,6 +1919,7 @@ enum sev_cmd_id { >> >> /* SNP specific commands */ >> KVM_SEV_SNP_INIT, >> + KVM_SEV_SNP_LAUNCH_START, >> >> KVM_SEV_NR_MAX, >> }; >> @@ -2026,6 +2027,15 @@ struct kvm_snp_init { >> __u64 flags; >> }; >> >> +struct kvm_sev_snp_launch_start { >> + __u64 policy; >> + __u64 ma_uaddr; >> + __u8 ma_en; >> + __u8 imi_en; >> + __u8 gosvw[16]; >> + __u8 pad[6]; >> +}; >> + >> #define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0) >> #define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1) >> #define KVM_DEV_ASSIGN_MASK_INTX (1 << 2) >
On 20.02.2023 20:38, Michael Roth wrote: > From: Brijesh Singh <brijesh.singh@amd.com> > > > +static int snp_decommission_context(struct kvm *kvm) > +{ > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > + struct sev_data_snp_addr data = {}; > + int ret; > + > + /* If context is not created then do nothing */ > + if (!sev->snp_context) > + return 0; > + > + data.gctx_paddr = __sme_pa(sev->snp_context); > + ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL); > + if (WARN_ONCE(ret, "failed to release guest context")) > + return ret; > + > + /* free the context page now */ > + snp_free_firmware_page(sev->snp_context); > + sev->snp_context = NULL; > + > + return 0; > +} > + Even though it's not documented, SNP_DECOMMISSION seems to clear the WBINVD indicator just like DEACTIVATE does for SEV. Won't ASID recycling race with SNP_DECOMMISSION if the latter isn't guarded with sev_deactivate_lock? > void sev_vm_destroy(struct kvm *kvm) > { > struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > @@ -2333,7 +2440,15 @@ void sev_vm_destroy(struct kvm *kvm) > } > } > > - sev_unbind_asid(kvm, sev->handle); > + if (sev_snp_guest(kvm)) { > + if (snp_decommission_context(kvm)) { > + WARN_ONCE(1, "Failed to free SNP guest context, leaking asid!\n"); > + return; > + } > + } else { > + sev_unbind_asid(kvm, sev->handle); > + } > + > sev_asid_free(sev); > } > Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.
On 4/26/23 12:06, Sabin Rapan wrote: > On 20.02.2023 20:38, Michael Roth wrote: >> From: Brijesh Singh <brijesh.singh@amd.com> >> >> >> +static int snp_decommission_context(struct kvm *kvm) >> +{ >> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >> + struct sev_data_snp_addr data = {}; >> + int ret; >> + >> + /* If context is not created then do nothing */ >> + if (!sev->snp_context) >> + return 0; >> + >> + data.gctx_paddr = __sme_pa(sev->snp_context); >> + ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL); >> + if (WARN_ONCE(ret, "failed to release guest context")) >> + return ret; >> + >> + /* free the context page now */ >> + snp_free_firmware_page(sev->snp_context); >> + sev->snp_context = NULL; >> + >> + return 0; >> +} >> + > > Even though it's not documented, SNP_DECOMMISSION seems to clear the > WBINVD indicator just like DEACTIVATE does for SEV. > Won't ASID recycling race with SNP_DECOMMISSION if the latter isn't > guarded with sev_deactivate_lock? Good catch, yes, this needs to use the sev_deactivate_lock around the DECOMMISSION command. Thanks, Tom > > >> void sev_vm_destroy(struct kvm *kvm) >> { >> struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >> @@ -2333,7 +2440,15 @@ void sev_vm_destroy(struct kvm *kvm) >> } >> } >> >> - sev_unbind_asid(kvm, sev->handle); >> + if (sev_snp_guest(kvm)) { >> + if (snp_decommission_context(kvm)) { >> + WARN_ONCE(1, "Failed to free SNP guest context, leaking asid!\n"); >> + return; >> + } >> + } else { >> + sev_unbind_asid(kvm, sev->handle); >> + } >> + >> sev_asid_free(sev); >> } >> > > > > Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.
diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst index 2432213bd0ea..58971fc02a15 100644 --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst @@ -461,6 +461,30 @@ The flags bitmap is defined as:: If the specified flags is not supported then return -EOPNOTSUPP, and the supported flags are returned. +19. KVM_SNP_LAUNCH_START +------------------------ + +The KVM_SNP_LAUNCH_START command is used for creating the memory encryption +context for the SEV-SNP guest. To create the encryption context, user must +provide a guest policy, migration agent (if any) and guest OS visible +workarounds value as defined SEV-SNP specification. + +Parameters (in): struct kvm_snp_launch_start + +Returns: 0 on success, -negative on error + +:: + + struct kvm_sev_snp_launch_start { + __u64 policy; /* Guest policy to use. */ + __u64 ma_uaddr; /* userspace address of migration agent */ + __u8 ma_en; /* 1 if the migration agent is enabled */ + __u8 imi_en; /* set IMI to 1. */ + __u8 gosvw[16]; /* guest OS visible workarounds */ + }; + +See the SEV-SNP specification for further detail on the launch input. + References ========== diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index a8efe1f6bf77..097bb2138360 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -22,6 +22,7 @@ #include <asm/pkru.h> #include <asm/trapnr.h> #include <asm/fpu/xcr.h> +#include <asm/sev.h> #include "mmu.h" #include "x86.h" @@ -75,6 +76,8 @@ static unsigned int nr_asids; static unsigned long *sev_asid_bitmap; static unsigned long *sev_reclaim_asid_bitmap; +static int snp_decommission_context(struct kvm *kvm); + struct enc_region { struct list_head list; unsigned long npages; @@ -100,12 +103,17 @@ static int sev_flush_asids(int min_asid, int max_asid) down_write(&sev_deactivate_lock); wbinvd_on_all_cpus(); - ret = sev_guest_df_flush(&error); + + if (sev_snp_enabled) + ret = sev_do_cmd(SEV_CMD_SNP_DF_FLUSH, NULL, &error); + else + ret = sev_guest_df_flush(&error); up_write(&sev_deactivate_lock); if (ret) - pr_err("SEV: DF_FLUSH failed, ret=%d, error=%#x\n", ret, error); + pr_err("SEV%s: DF_FLUSH failed, ret=%d, error=%#x\n", + sev_snp_enabled ? "-SNP" : "", ret, error); return ret; } @@ -2011,6 +2019,80 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd) return ret; } +/* + * The guest context contains all the information, keys and metadata + * associated with the guest that the firmware tracks to implement SEV + * and SNP features. The firmware stores the guest context in hypervisor + * provide page via the SNP_GCTX_CREATE command. + */ +static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp) +{ + struct sev_data_snp_addr data = {}; + void *context; + int rc; + + /* Allocate memory for context page */ + context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT); + if (!context) + return NULL; + + data.gctx_paddr = __psp_pa(context); + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_GCTX_CREATE, &data, &argp->error); + if (rc) { + snp_free_firmware_page(context); + return NULL; + } + + return context; +} + +static int snp_bind_asid(struct kvm *kvm, int *error) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + struct sev_data_snp_activate data = {0}; + + data.gctx_paddr = __psp_pa(sev->snp_context); + data.asid = sev_get_asid(kvm); + return sev_issue_cmd(kvm, SEV_CMD_SNP_ACTIVATE, &data, error); +} + +static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + struct sev_data_snp_launch_start start = {0}; + struct kvm_sev_snp_launch_start params; + int rc; + + if (!sev_snp_guest(kvm)) + return -ENOTTY; + + if (copy_from_user(¶ms, (void __user *)(uintptr_t)argp->data, sizeof(params))) + return -EFAULT; + + sev->snp_context = snp_context_create(kvm, argp); + if (!sev->snp_context) + return -ENOTTY; + + start.gctx_paddr = __psp_pa(sev->snp_context); + start.policy = params.policy; + memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw)); + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error); + if (rc) + goto e_free_context; + + sev->fd = argp->sev_fd; + rc = snp_bind_asid(kvm, &argp->error); + if (rc) + goto e_free_context; + + return 0; + +e_free_context: + snp_decommission_context(kvm); + + return rc; +} + int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp) { struct kvm_sev_cmd sev_cmd; @@ -2101,6 +2183,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp) case KVM_SEV_RECEIVE_FINISH: r = sev_receive_finish(kvm, &sev_cmd); break; + case KVM_SEV_SNP_LAUNCH_START: + r = snp_launch_start(kvm, &sev_cmd); + break; default: r = -EINVAL; goto out; @@ -2292,6 +2377,28 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd) return ret; } +static int snp_decommission_context(struct kvm *kvm) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + struct sev_data_snp_addr data = {}; + int ret; + + /* If context is not created then do nothing */ + if (!sev->snp_context) + return 0; + + data.gctx_paddr = __sme_pa(sev->snp_context); + ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL); + if (WARN_ONCE(ret, "failed to release guest context")) + return ret; + + /* free the context page now */ + snp_free_firmware_page(sev->snp_context); + sev->snp_context = NULL; + + return 0; +} + void sev_vm_destroy(struct kvm *kvm) { struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; @@ -2333,7 +2440,15 @@ void sev_vm_destroy(struct kvm *kvm) } } - sev_unbind_asid(kvm, sev->handle); + if (sev_snp_guest(kvm)) { + if (snp_decommission_context(kvm)) { + WARN_ONCE(1, "Failed to free SNP guest context, leaking asid!\n"); + return; + } + } else { + sev_unbind_asid(kvm, sev->handle); + } + sev_asid_free(sev); } diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 56a5c96d8a36..740969b57425 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -92,6 +92,7 @@ struct kvm_sev_info { struct misc_cg *misc_cg; /* For misc cgroup accounting */ atomic_t migration_in_progress; u64 snp_init_flags; + void *snp_context; /* SNP guest context page */ }; struct kvm_svm { diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 499cc323f793..cf19799ca5ce 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1919,6 +1919,7 @@ enum sev_cmd_id { /* SNP specific commands */ KVM_SEV_SNP_INIT, + KVM_SEV_SNP_LAUNCH_START, KVM_SEV_NR_MAX, }; @@ -2026,6 +2027,15 @@ struct kvm_snp_init { __u64 flags; }; +struct kvm_sev_snp_launch_start { + __u64 policy; + __u64 ma_uaddr; + __u8 ma_en; + __u8 imi_en; + __u8 gosvw[16]; + __u8 pad[6]; +}; + #define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0) #define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1) #define KVM_DEV_ASSIGN_MASK_INTX (1 << 2)