@@ -404,8 +404,6 @@ bool kvm_arch_stop_on_emulation_error(CPUState *cpu);
int kvm_check_extension(KVMState *s, unsigned int extension);
-int kvm_vm_check_extension(KVMState *s, unsigned int extension);
-
#define kvm_vm_enable_cap(s, capability, cap_flags, ...) \
({ \
struct kvm_enable_cap cap = { \
@@ -123,6 +123,7 @@ struct KVMState
uint16_t xen_gnttab_max_frames;
uint16_t xen_evtchn_max_pirq;
char *device;
+ bool check_extension_vm;
};
void kvm_memory_listener_register(KVMState *s, KVMMemoryListener *kml,
@@ -1128,7 +1128,11 @@ int kvm_check_extension(KVMState *s, unsigned int extension)
{
int ret;
- ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, extension);
+ if (!s->check_extension_vm) {
+ ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, extension);
+ } else {
+ ret = kvm_vm_ioctl(s, KVM_CHECK_EXTENSION, extension);
+ }
if (ret < 0) {
ret = 0;
}
@@ -1136,19 +1140,6 @@ int kvm_check_extension(KVMState *s, unsigned int extension)
return ret;
}
-int kvm_vm_check_extension(KVMState *s, unsigned int extension)
-{
- int ret;
-
- ret = kvm_vm_ioctl(s, KVM_CHECK_EXTENSION, extension);
- if (ret < 0) {
- /* VM wide version not implemented, use global one instead */
- ret = kvm_check_extension(s, extension);
- }
-
- return ret;
-}
-
/*
* We track the poisoned pages to be able to:
* - replace them on VM reset
@@ -1515,10 +1506,10 @@ static int kvm_dirty_ring_init(KVMState *s)
* Read the max supported pages. Fall back to dirty logging mode
* if the dirty ring isn't supported.
*/
- ret = kvm_vm_check_extension(s, capability);
+ ret = kvm_check_extension(s, capability);
if (ret <= 0) {
capability = KVM_CAP_DIRTY_LOG_RING_ACQ_REL;
- ret = kvm_vm_check_extension(s, capability);
+ ret = kvm_check_extension(s, capability);
}
if (ret <= 0) {
@@ -1541,7 +1532,7 @@ static int kvm_dirty_ring_init(KVMState *s)
}
/* Enable the backup bitmap if it is supported */
- ret = kvm_vm_check_extension(s, KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP);
+ ret = kvm_check_extension(s, KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP);
if (ret > 0) {
ret = kvm_vm_enable_cap(s, KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP, 0);
if (ret) {
@@ -2360,7 +2351,7 @@ static void kvm_irqchip_create(KVMState *s)
*/
static int kvm_recommended_vcpus(KVMState *s)
{
- int ret = kvm_vm_check_extension(s, KVM_CAP_NR_VCPUS);
+ int ret = kvm_check_extension(s, KVM_CAP_NR_VCPUS);
return (ret) ? ret : 4;
}
@@ -2526,6 +2517,11 @@ static int kvm_init(MachineState *ms)
s->vmfd = ret;
+ ret = kvm_vm_ioctl(s, KVM_CHECK_EXTENSION, KVM_CAP_CHECK_EXTENSION_VM);
+ if (ret > 0) {
+ s->check_extension_vm = true;
+ }
+
/* check the vcpu limits */
soft_vcpus_limit = kvm_recommended_vcpus(s);
hard_vcpus_limit = kvm_max_vcpus(s);
@@ -2668,7 +2664,7 @@ static int kvm_init(MachineState *ms)
memory_listener_register(&kvm_io_listener,
&address_space_io);
- s->sync_mmu = !!kvm_vm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);
+ s->sync_mmu = !!kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);
if (!s->sync_mmu) {
ret = ram_block_discard_disable(true);
assert(!ret);
@@ -582,7 +582,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
if (s->kvm_eager_split_size) {
uint32_t sizes;
- sizes = kvm_vm_check_extension(s, KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES);
+ sizes = kvm_check_extension(s, KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES);
if (!sizes) {
s->kvm_eager_split_size = 0;
warn_report("Eager Page Split support not available");
@@ -163,7 +163,7 @@ static int kvm_get_one_msr(X86CPU *cpu, int index, uint64_t *value);
bool kvm_has_smm(void)
{
- return kvm_vm_check_extension(kvm_state, KVM_CAP_X86_SMM);
+ return kvm_check_extension(kvm_state, KVM_CAP_X86_SMM);
}
bool kvm_has_adjust_clock_stable(void)
@@ -2697,7 +2697,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
return ret;
}
}
- if (kvm_vm_check_extension(s, KVM_CAP_X86_USER_SPACE_MSR)) {
+ if (kvm_check_extension(s, KVM_CAP_X86_USER_SPACE_MSR)) {
bool r;
ret = kvm_vm_enable_cap(s, KVM_CAP_X86_USER_SPACE_MSR, 0,
@@ -5236,7 +5236,7 @@ static bool __kvm_enable_sgx_provisioning(KVMState *s)
{
int fd, ret;
- if (!kvm_vm_check_extension(s, KVM_CAP_SGX_ATTRIBUTE)) {
+ if (!kvm_check_extension(s, KVM_CAP_SGX_ATTRIBUTE)) {
return false;
}
@@ -101,7 +101,7 @@ static uint32_t debug_inst_opcode;
static bool kvmppc_is_pr(KVMState *ks)
{
/* Assume KVM-PR if the GET_PVINFO capability is available */
- return kvm_vm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
+ return kvm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
}
static int kvm_ppc_register_host_cpu_type(void);
@@ -118,11 +118,11 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
cap_interrupt_unset = kvm_check_extension(s, KVM_CAP_PPC_UNSET_IRQ);
cap_segstate = kvm_check_extension(s, KVM_CAP_PPC_SEGSTATE);
cap_booke_sregs = kvm_check_extension(s, KVM_CAP_PPC_BOOKE_SREGS);
- cap_ppc_smt_possible = kvm_vm_check_extension(s, KVM_CAP_PPC_SMT_POSSIBLE);
+ cap_ppc_smt_possible = kvm_check_extension(s, KVM_CAP_PPC_SMT_POSSIBLE);
cap_spapr_tce = kvm_check_extension(s, KVM_CAP_SPAPR_TCE);
cap_spapr_tce_64 = kvm_check_extension(s, KVM_CAP_SPAPR_TCE_64);
cap_spapr_multitce = kvm_check_extension(s, KVM_CAP_SPAPR_MULTITCE);
- cap_spapr_vfio = kvm_vm_check_extension(s, KVM_CAP_SPAPR_TCE_VFIO);
+ cap_spapr_vfio = kvm_check_extension(s, KVM_CAP_SPAPR_TCE_VFIO);
cap_one_reg = kvm_check_extension(s, KVM_CAP_ONE_REG);
cap_hior = kvm_check_extension(s, KVM_CAP_PPC_HIOR);
cap_epr = kvm_check_extension(s, KVM_CAP_PPC_EPR);
@@ -131,23 +131,23 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
* Note: we don't set cap_papr here, because this capability is
* only activated after this by kvmppc_set_papr()
*/
- cap_htab_fd = kvm_vm_check_extension(s, KVM_CAP_PPC_HTAB_FD);
+ cap_htab_fd = kvm_check_extension(s, KVM_CAP_PPC_HTAB_FD);
cap_fixup_hcalls = kvm_check_extension(s, KVM_CAP_PPC_FIXUP_HCALL);
- cap_ppc_smt = kvm_vm_check_extension(s, KVM_CAP_PPC_SMT);
- cap_htm = kvm_vm_check_extension(s, KVM_CAP_PPC_HTM);
- cap_mmu_radix = kvm_vm_check_extension(s, KVM_CAP_PPC_MMU_RADIX);
- cap_mmu_hash_v3 = kvm_vm_check_extension(s, KVM_CAP_PPC_MMU_HASH_V3);
- cap_xive = kvm_vm_check_extension(s, KVM_CAP_PPC_IRQ_XIVE);
- cap_resize_hpt = kvm_vm_check_extension(s, KVM_CAP_SPAPR_RESIZE_HPT);
+ cap_ppc_smt = kvm_check_extension(s, KVM_CAP_PPC_SMT);
+ cap_htm = kvm_check_extension(s, KVM_CAP_PPC_HTM);
+ cap_mmu_radix = kvm_check_extension(s, KVM_CAP_PPC_MMU_RADIX);
+ cap_mmu_hash_v3 = kvm_check_extension(s, KVM_CAP_PPC_MMU_HASH_V3);
+ cap_xive = kvm_check_extension(s, KVM_CAP_PPC_IRQ_XIVE);
+ cap_resize_hpt = kvm_check_extension(s, KVM_CAP_SPAPR_RESIZE_HPT);
kvmppc_get_cpu_characteristics(s);
- cap_ppc_nested_kvm_hv = kvm_vm_check_extension(s, KVM_CAP_PPC_NESTED_HV);
+ cap_ppc_nested_kvm_hv = kvm_check_extension(s, KVM_CAP_PPC_NESTED_HV);
cap_large_decr = kvmppc_get_dec_bits();
- cap_fwnmi = kvm_vm_check_extension(s, KVM_CAP_PPC_FWNMI);
+ cap_fwnmi = kvm_check_extension(s, KVM_CAP_PPC_FWNMI);
/*
* Note: setting it to false because there is not such capability
* in KVM at this moment.
*
- * TODO: call kvm_vm_check_extension() with the right capability
+ * TODO: call kvm_check_extension() with the right capability
* after the kernel starts implementing it.
*/
cap_ppc_pvr_compat = false;
@@ -157,8 +157,8 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
exit(1);
}
- cap_rpt_invalidate = kvm_vm_check_extension(s, KVM_CAP_PPC_RPT_INVALIDATE);
- cap_ail_mode_3 = kvm_vm_check_extension(s, KVM_CAP_PPC_AIL_MODE_3);
+ cap_rpt_invalidate = kvm_check_extension(s, KVM_CAP_PPC_RPT_INVALIDATE);
+ cap_ail_mode_3 = kvm_check_extension(s, KVM_CAP_PPC_AIL_MODE_3);
kvm_ppc_register_host_cpu_type();
return 0;
@@ -1969,7 +1969,7 @@ static int kvmppc_get_pvinfo(CPUPPCState *env, struct kvm_ppc_pvinfo *pvinfo)
{
CPUState *cs = env_cpu(env);
- if (kvm_vm_check_extension(cs->kvm_state, KVM_CAP_PPC_GET_PVINFO) &&
+ if (kvm_check_extension(cs->kvm_state, KVM_CAP_PPC_GET_PVINFO) &&
!kvm_vm_ioctl(cs->kvm_state, KVM_PPC_GET_PVINFO, pvinfo)) {
return 0;
}
@@ -2289,7 +2289,7 @@ int kvmppc_reset_htab(int shift_hint)
/* Full emulation, tell caller to allocate htab itself */
return 0;
}
- if (kvm_vm_check_extension(kvm_state, KVM_CAP_PPC_ALLOC_HTAB)) {
+ if (kvm_check_extension(kvm_state, KVM_CAP_PPC_ALLOC_HTAB)) {
int ret;
ret = kvm_vm_ioctl(kvm_state, KVM_PPC_ALLOCATE_HTAB, &shift);
if (ret == -ENOTTY) {
@@ -2474,7 +2474,7 @@ static void kvmppc_get_cpu_characteristics(KVMState *s)
cap_ppc_safe_bounds_check = 0;
cap_ppc_safe_indirect_branch = 0;
- ret = kvm_vm_check_extension(s, KVM_CAP_PPC_GET_CPU_CHAR);
+ ret = kvm_check_extension(s, KVM_CAP_PPC_GET_CPU_CHAR);
if (!ret) {
return;
}
The KVM_CHECK_EXTENSION ioctl can be issued either on the global fd (/dev/kvm), or on the VM fd obtained with KVM_CREATE_VM. For most extensions, KVM returns the same value with either method, but for some of them it can refine the returned value depending on the VM type. The KVM documentation [1] advises to use the VM fd: Based on their initialization different VMs may have different capabilities. It is thus encouraged to use the vm ioctl to query for capabilities (available with KVM_CAP_CHECK_EXTENSION_VM on the vm fd) Ongoing work on Arm confidential VMs confirms this, as some capabilities become unavailable to confidential VMs, requiring changes in QEMU to use kvm_vm_check_extension() instead of kvm_check_extension() [2]. Rather than changing each check one by one, change kvm_check_extension() to always issue the ioctl on the VM fd when available, and remove kvm_vm_check_extension(). Fall back to the global fd when the VM check is unavailable: * Ancient kernels do not support KVM_CHECK_EXTENSION on the VM fd, since it was added by commit 92b591a4c46b ("KVM: Allow KVM_CHECK_EXTENSION on the vm fd") in Linux 3.17 [3]. Support for Linux 3.16 ended in June 2020, but there may still be old images around. * A couple of calls must be issued before the VM fd is available, since they determine the VM type: KVM_CAP_MIPS_VZ and KVM_CAP_ARM_VM_IPA_SIZE Does any user actually depend on the check being done on the global fd instead of the VM fd? I surveyed all cases where KVM presently returns different values depending on the query method. Luckily QEMU already calls kvm_vm_check_extension() for most of those. Only three of them are ambiguous, because currently done on the global fd: * KVM_CAP_MAX_VCPUS and KVM_CAP_MAX_VCPU_ID on Arm, changes value if the user requests a vGIC different from the default. But QEMU queries this before vGIC configuration, so the reported value will be the same. * KVM_CAP_SW_TLB on PPC. When issued on the global fd, returns false if the kvm-hv module is loaded; when issued on the VM fd, returns false only if the VM type is HV instead of PR. If this returns false, then QEMU will fail to initialize a BOOKE206 MMU model. So this patch supposedly improves things, as it allows to run this type of vCPU even when both KVM modules are loaded. * KVM_CAP_PPC_SECURE_GUEST. Similarly, doing this check on a VM fd refines the returned value, and ensures that SVM is actually supported. Since QEMU follows the check with kvm_vm_enable_cap(), this patch should only provide better error reporting. [1] https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-check-extension [2] https://lore.kernel.org/kvm/875ybi0ytc.fsf@redhat.com/ [3] https://github.com/torvalds/linux/commit/92b591a4c46b Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Daniel Henrique Barboza <danielhb413@gmail.com> Cc: qemu-ppc@nongnu.org Suggested-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> --- v1: https://lore.kernel.org/qemu-devel/20230421163822.839167-1-jean-philippe@linaro.org/ v1->v2: Initialize check_extension_vm using kvm_vm_ioctl() as suggested --- include/sysemu/kvm.h | 2 -- include/sysemu/kvm_int.h | 1 + accel/kvm/kvm-all.c | 34 +++++++++++++++------------------- target/arm/kvm.c | 2 +- target/i386/kvm/kvm.c | 6 +++--- target/ppc/kvm.c | 36 ++++++++++++++++++------------------ 6 files changed, 38 insertions(+), 43 deletions(-)