* [PATCH v2 0/3] KVM: x86: Virtualize AMD CPUID faulting
@ 2026-05-08 17:07 Jim Mattson
2026-05-08 17:07 ` [PATCH v2 1/3] KVM: x86: Remove supports_cpuid_fault() helper Jim Mattson
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Jim Mattson @ 2026-05-08 17:07 UTC (permalink / raw)
To: Sean Christopherson, Paolo Bonzini, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, Dave Hansen, x86, H. Peter Anvin, Shuah Khan,
kvm, linux-kernel, linux-kselftest, Clayton Pence
Cc: Jim Mattson
AMD's "disable CPUID in usermode" feature is analogous to Intel's "CPUID
faulting" feature, but it is advertised and activated differently. The AMD
feature is advertised via CPUID.80000021H:EAX.CpuidUserDis[bit 17] and
activated by setting HWCR.CpuidUserDis[bit 35].
Add virtualization support for the AMD feature.
v1 -> v2:
* Remove supports_cpuid_fault() instead of renaming it [Sean]
v1: https://lore.kernel.org/kvm/20260402223108.650572-1-jmattson@google.com/
Jim Mattson (3):
KVM: x86: Remove supports_cpuid_fault() helper
KVM: x86: Virtualize AMD CPUID faulting
KVM: selftests: Update hwcr_msr_test for CPUID faulting bit
arch/x86/kvm/cpuid.c | 2 +-
arch/x86/kvm/cpuid.h | 11 ++++------
arch/x86/kvm/emulate.c | 14 +++++++------
arch/x86/kvm/x86.c | 21 ++++++++++++-------
.../testing/selftests/kvm/x86/hwcr_msr_test.c | 10 ++++-----
5 files changed, 32 insertions(+), 26 deletions(-)
base-commit: 85f871f6ba46f20d7fbc0b016b4db648c33220dd
--
2.54.0.563.g4f69b47b94-goog
^ permalink raw reply [flat|nested] 7+ messages in thread* [PATCH v2 1/3] KVM: x86: Remove supports_cpuid_fault() helper 2026-05-08 17:07 [PATCH v2 0/3] KVM: x86: Virtualize AMD CPUID faulting Jim Mattson @ 2026-05-08 17:07 ` Jim Mattson 2026-05-08 17:07 ` [PATCH v2 2/3] KVM: x86: Virtualize AMD CPUID faulting Jim Mattson 2026-05-08 17:07 ` [PATCH v2 3/3] KVM: selftests: Update hwcr_msr_test for CPUID faulting bit Jim Mattson 2 siblings, 0 replies; 7+ messages in thread From: Jim Mattson @ 2026-05-08 17:07 UTC (permalink / raw) To: Sean Christopherson, Paolo Bonzini, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin, Shuah Khan, kvm, linux-kernel, linux-kselftest, Clayton Pence Cc: Jim Mattson The function, supports_cpuid_fault(), tests specifically for guest support of Intel's CPUID faulting feature. It does not test for guest support of AMD's CPUID faulting feature. To avoid confusion, remove the helper. Signed-off-by: Jim Mattson <jmattson@google.com> --- arch/x86/kvm/cpuid.h | 5 ----- arch/x86/kvm/x86.c | 2 +- 2 files changed, 1 insertion(+), 6 deletions(-) diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 039b8e6f40ba..8b64d863e19c 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -181,11 +181,6 @@ static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu) return x86_stepping(best->eax); } -static inline bool supports_cpuid_fault(struct kvm_vcpu *vcpu) -{ - return vcpu->arch.msr_platform_info & MSR_PLATFORM_INFO_CPUID_FAULT; -} - static inline bool cpuid_fault_enabled(struct kvm_vcpu *vcpu) { return vcpu->arch.msr_misc_features_enables & diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 0a1b63c63d1a..7d5b66287593 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4264,7 +4264,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_MISC_FEATURES_ENABLES: if (data & ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT || (data & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT && - !supports_cpuid_fault(vcpu))) + !(vcpu->arch.msr_platform_info & MSR_PLATFORM_INFO_CPUID_FAULT))) return 1; vcpu->arch.msr_misc_features_enables = data; break; -- 2.54.0.563.g4f69b47b94-goog ^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 2/3] KVM: x86: Virtualize AMD CPUID faulting 2026-05-08 17:07 [PATCH v2 0/3] KVM: x86: Virtualize AMD CPUID faulting Jim Mattson 2026-05-08 17:07 ` [PATCH v2 1/3] KVM: x86: Remove supports_cpuid_fault() helper Jim Mattson @ 2026-05-08 17:07 ` Jim Mattson 2026-05-12 21:33 ` Sean Christopherson 2026-05-08 17:07 ` [PATCH v2 3/3] KVM: selftests: Update hwcr_msr_test for CPUID faulting bit Jim Mattson 2 siblings, 1 reply; 7+ messages in thread From: Jim Mattson @ 2026-05-08 17:07 UTC (permalink / raw) To: Sean Christopherson, Paolo Bonzini, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin, Shuah Khan, kvm, linux-kernel, linux-kselftest, Clayton Pence Cc: Jim Mattson On AMD CPUs, CPUID faulting support is advertised via CPUID.80000021H:EAX.CpuidUserDis[bit 17] and enabled by setting HWCR.CpuidUserDis[bit 35]. Advertise the feature to userspace regardless of host CPU support. Allow writes to HWCR to set bit 35 when the guest CPUID advertises CpuidUserDis. Update cpuid_fault_enabled() and em_cpuid() to check HWCR.CpuidUserDis[bit 35] as well as MSR_FEATURE_ENABLES.CPUID_GP_ON_CPL_GT_0[bit 0]. Signed-off-by: Jim Mattson <jmattson@google.com> --- arch/x86/kvm/cpuid.c | 2 +- arch/x86/kvm/cpuid.h | 6 ++++-- arch/x86/kvm/emulate.c | 14 ++++++++------ arch/x86/kvm/x86.c | 19 +++++++++++++------ 4 files changed, 26 insertions(+), 15 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index e69156b54cff..db54fac61da9 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -1248,7 +1248,7 @@ void kvm_initialize_cpu_caps(void) F(AUTOIBRS), EMULATED_F(NO_SMM_CTL_MSR), /* PrefetchCtlMsr */ - /* GpOnUserCpuid */ + EMULATED_F(GP_ON_USER_CPUID), /* EPSF */ F(PREFETCHI), F(AVX512_BMM), diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 8b64d863e19c..7312cb0591f4 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -183,8 +183,10 @@ static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu) static inline bool cpuid_fault_enabled(struct kvm_vcpu *vcpu) { - return vcpu->arch.msr_misc_features_enables & - MSR_MISC_FEATURES_ENABLES_CPUID_FAULT; + return (vcpu->arch.msr_misc_features_enables & + MSR_MISC_FEATURES_ENABLES_CPUID_FAULT) || + (vcpu->arch.msr_hwcr & + BIT_ULL(MSR_K7_HWCR_CPUID_USER_DIS_BIT)); } static __always_inline void kvm_cpu_cap_clear(unsigned int x86_feature) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index c8c6cc0406d6..127d031d3310 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3593,13 +3593,15 @@ static int em_sti(struct x86_emulate_ctxt *ctxt) static int em_cpuid(struct x86_emulate_ctxt *ctxt) { u32 eax, ebx, ecx, edx; - u64 msr = 0; + u64 msr[2] = {}; - ctxt->ops->get_msr(ctxt, MSR_MISC_FEATURES_ENABLES, &msr); - if (!ctxt->ops->is_smm(ctxt) && - (msr & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT) && - ctxt->ops->cpl(ctxt)) - return emulate_gp(ctxt, 0); + if (!ctxt->ops->is_smm(ctxt) && ctxt->ops->cpl(ctxt)) { + ctxt->ops->get_msr(ctxt, MSR_MISC_FEATURES_ENABLES, &msr[0]); + ctxt->ops->get_msr(ctxt, MSR_K7_HWCR, &msr[1]); + if ((msr[0] & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT) || + (msr[1] & BIT_ULL(MSR_K7_HWCR_CPUID_USER_DIS_BIT))) + return emulate_gp(ctxt, 0); + } eax = reg_read(ctxt, VCPU_REGS_RAX); ecx = reg_read(ctxt, VCPU_REGS_RCX); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7d5b66287593..5f64f67ba083 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4002,22 +4002,29 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) break; case MSR_EFER: return set_efer(vcpu, msr_info); - case MSR_K7_HWCR: - data &= ~(u64)0x40; /* ignore flush filter disable */ - data &= ~(u64)0x100; /* ignore ignne emulation enable */ - data &= ~(u64)0x8; /* ignore TLB cache disable */ - + case MSR_K7_HWCR: { /* * Allow McStatusWrEn and TscFreqSel. (Linux guests from v3.2 * through at least v6.6 whine if TscFreqSel is clear, * depending on F/M/S. */ - if (data & ~(BIT_ULL(18) | BIT_ULL(24))) { + u64 valid = BIT_ULL(18) | BIT_ULL(24); + + data &= ~(u64)0x40; /* ignore flush filter disable */ + data &= ~(u64)0x100; /* ignore ignne emulation enable */ + data &= ~(u64)0x8; /* ignore TLB cache disable */ + + if (guest_cpu_cap_has(vcpu, X86_FEATURE_GP_ON_USER_CPUID)) + valid |= BIT_ULL(MSR_K7_HWCR_CPUID_USER_DIS_BIT); + + + if (data & ~valid) { kvm_pr_unimpl_wrmsr(vcpu, msr, data); return 1; } vcpu->arch.msr_hwcr = data; break; + } case MSR_FAM10H_MMIO_CONF_BASE: if (data != 0) { kvm_pr_unimpl_wrmsr(vcpu, msr, data); -- 2.54.0.563.g4f69b47b94-goog ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/3] KVM: x86: Virtualize AMD CPUID faulting 2026-05-08 17:07 ` [PATCH v2 2/3] KVM: x86: Virtualize AMD CPUID faulting Jim Mattson @ 2026-05-12 21:33 ` Sean Christopherson 2026-05-13 0:01 ` Jim Mattson 0 siblings, 1 reply; 7+ messages in thread From: Sean Christopherson @ 2026-05-12 21:33 UTC (permalink / raw) To: Jim Mattson Cc: Paolo Bonzini, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin, Shuah Khan, kvm, linux-kernel, linux-kselftest, Clayton Pence On Fri, May 08, 2026, Jim Mattson wrote: > static __always_inline void kvm_cpu_cap_clear(unsigned int x86_feature) > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index c8c6cc0406d6..127d031d3310 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -3593,13 +3593,15 @@ static int em_sti(struct x86_emulate_ctxt *ctxt) > static int em_cpuid(struct x86_emulate_ctxt *ctxt) > { > u32 eax, ebx, ecx, edx; > - u64 msr = 0; > + u64 msr[2] = {}; > > - ctxt->ops->get_msr(ctxt, MSR_MISC_FEATURES_ENABLES, &msr); > - if (!ctxt->ops->is_smm(ctxt) && > - (msr & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT) && > - ctxt->ops->cpl(ctxt)) > - return emulate_gp(ctxt, 0); > + if (!ctxt->ops->is_smm(ctxt) && ctxt->ops->cpl(ctxt)) { > + ctxt->ops->get_msr(ctxt, MSR_MISC_FEATURES_ENABLES, &msr[0]); > + ctxt->ops->get_msr(ctxt, MSR_K7_HWCR, &msr[1]); > + if ((msr[0] & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT) || > + (msr[1] & BIT_ULL(MSR_K7_HWCR_CPUID_USER_DIS_BIT))) Hrm, this is all rather ugly (definitely not your fault). What do you think about adding x86_emulate_ops.cpuid_fault_enabled() to at least get deduplicate the MSR lookups? Gah, we should do more than that. I was going to say, "If it weren't for kvm_emulate_cpuid() using kvm_require_cpl(), we could roll *all* of the checks into cpuid_fault_enabled()". But that's a rather stupid reason to duplicate the code, because kvm_emulate_cpuid() is literally the only user of kvm_require_cpl(). Pulling smm.h into cpuid.h isn't great, but the code is much nicer, especially the next patch to add AMD CPUID faulting. Compile tested only... --- From: Sean Christopherson <seanjc@google.com> Date: Tue, 12 May 2026 14:20:47 -0700 Subject: [PATCH 1/3] KVM: x86: Consolidate CPUID fault handling for emulator and interception logic Extract the logic for emulating CPUID faulting (where CPUID #GPs at CPL>0 outside of SMM) into a dedicated helper and use the helper for both the full emulator and the intercepted-CPUID paths. Opportunistically drop kvm_require_cpl(), as kvm_require_cpl() was the one and only user. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/cpuid.c | 5 +++-- arch/x86/kvm/cpuid.h | 8 ++++++++ arch/x86/kvm/emulate.c | 6 +----- arch/x86/kvm/kvm_emulate.h | 1 + arch/x86/kvm/x86.c | 18 ++++++------------ 6 files changed, 19 insertions(+), 20 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index c470e40a00aa..a9005c61619b 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2285,7 +2285,6 @@ void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned int nr, void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault); void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault); -bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl); bool kvm_require_dr(struct kvm_vcpu *vcpu, int dr); static inline int __kvm_irq_line_state(unsigned long *irq_state, diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index e69156b54cff..1c95d1fa3ead 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -2161,9 +2161,10 @@ int kvm_emulate_cpuid(struct kvm_vcpu *vcpu) { u32 eax, ebx, ecx, edx; - if (!is_smm(vcpu) && cpuid_fault_enabled(vcpu) && - !kvm_require_cpl(vcpu, 0)) + if (!kvm_is_cpuid_allowed(vcpu)) { + kvm_queue_exception_e(vcpu, GP_VECTOR, 0); return 1; + } eax = kvm_rax_read(vcpu); ecx = kvm_rcx_read(vcpu); diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 8b64d863e19c..95d09ccbf951 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -7,6 +7,8 @@ #include <asm/processor.h> #include <uapi/asm/kvm_para.h> +#include "smm.h" + extern u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly; extern bool kvm_is_configuring_cpu_caps __read_mostly; @@ -187,6 +189,12 @@ static inline bool cpuid_fault_enabled(struct kvm_vcpu *vcpu) MSR_MISC_FEATURES_ENABLES_CPUID_FAULT; } +static inline bool kvm_is_cpuid_allowed(struct kvm_vcpu *vcpu) +{ + return !cpuid_fault_enabled(vcpu) || is_smm(vcpu) || + !kvm_x86_call(get_cpl)(vcpu); +} + static __always_inline void kvm_cpu_cap_clear(unsigned int x86_feature) { unsigned int x86_leaf = __feature_leaf(x86_feature); diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index c8c6cc0406d6..3ba09093b5ab 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3593,12 +3593,8 @@ static int em_sti(struct x86_emulate_ctxt *ctxt) static int em_cpuid(struct x86_emulate_ctxt *ctxt) { u32 eax, ebx, ecx, edx; - u64 msr = 0; - ctxt->ops->get_msr(ctxt, MSR_MISC_FEATURES_ENABLES, &msr); - if (!ctxt->ops->is_smm(ctxt) && - (msr & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT) && - ctxt->ops->cpl(ctxt)) + if (!ctxt->ops->is_cpuid_allowed(ctxt)) return emulate_gp(ctxt, 0); eax = reg_read(ctxt, VCPU_REGS_RAX); diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h index 0abff36d0994..45d4a03b202e 100644 --- a/arch/x86/kvm/kvm_emulate.h +++ b/arch/x86/kvm/kvm_emulate.h @@ -225,6 +225,7 @@ struct x86_emulate_ops { struct x86_instruction_info *info, enum x86_intercept_stage stage); + bool (*is_cpuid_allowed)(struct x86_emulate_ctxt *ctxt); bool (*get_cpuid)(struct x86_emulate_ctxt *ctxt, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx, bool exact_only); bool (*guest_has_movbe)(struct x86_emulate_ctxt *ctxt); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7d5b66287593..c60773349f35 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1021,18 +1021,6 @@ void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code) } EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_queue_exception_e); -/* - * Checks if cpl <= required_cpl; if true, return true. Otherwise queue - * a #GP and return false. - */ -bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl) -{ - if (kvm_x86_call(get_cpl)(vcpu) <= required_cpl) - return true; - kvm_queue_exception_e(vcpu, GP_VECTOR, 0); - return false; -} - bool kvm_require_dr(struct kvm_vcpu *vcpu, int dr) { if ((dr != 4 && dr != 5) || !kvm_is_cr4_bit_set(vcpu, X86_CR4_DE)) @@ -8819,6 +8807,11 @@ static int emulator_intercept(struct x86_emulate_ctxt *ctxt, &ctxt->exception); } +static bool emulator_is_cpuid_allowed(struct x86_emulate_ctxt *ctxt) +{ + return kvm_is_cpuid_allowed(emul_to_vcpu(ctxt)); +} + static bool emulator_get_cpuid(struct x86_emulate_ctxt *ctxt, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx, bool exact_only) @@ -8955,6 +8948,7 @@ static const struct x86_emulate_ops emulate_ops = { .wbinvd = emulator_wbinvd, .fix_hypercall = emulator_fix_hypercall, .intercept = emulator_intercept, + .is_cpuid_allowed = emulator_is_cpuid_allowed, .get_cpuid = emulator_get_cpuid, .guest_has_movbe = emulator_guest_has_movbe, .guest_has_fxsr = emulator_guest_has_fxsr, base-commit: 41a2602f2947b91e237cd1ce85afcd162274470a -- ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/3] KVM: x86: Virtualize AMD CPUID faulting 2026-05-12 21:33 ` Sean Christopherson @ 2026-05-13 0:01 ` Jim Mattson 2026-05-13 0:04 ` Sean Christopherson 0 siblings, 1 reply; 7+ messages in thread From: Jim Mattson @ 2026-05-13 0:01 UTC (permalink / raw) To: Sean Christopherson Cc: Paolo Bonzini, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin, Shuah Khan, kvm, linux-kernel, linux-kselftest, Clayton Pence On Tue, May 12, 2026 at 2:33 PM Sean Christopherson <seanjc@google.com> wrote: > From: Sean Christopherson <seanjc@google.com> > Date: Tue, 12 May 2026 14:20:47 -0700 > Subject: [PATCH 1/3] KVM: x86: Consolidate CPUID fault handling for emulator > and interception logic > > Extract the logic for emulating CPUID faulting (where CPUID #GPs at CPL>0 > outside of SMM) into a dedicated helper and use the helper for both the > full emulator and the intercepted-CPUID paths. > > Opportunistically drop kvm_require_cpl(), as kvm_require_cpl() was the one > and only user. > > No functional change intended. > > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/include/asm/kvm_host.h | 1 - > arch/x86/kvm/cpuid.c | 5 +++-- > arch/x86/kvm/cpuid.h | 8 ++++++++ > arch/x86/kvm/emulate.c | 6 +----- > arch/x86/kvm/kvm_emulate.h | 1 + > arch/x86/kvm/x86.c | 18 ++++++------------ > 6 files changed, 19 insertions(+), 20 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index c470e40a00aa..a9005c61619b 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -2285,7 +2285,6 @@ void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned int nr, > void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault); > void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu, > struct x86_exception *fault); > -bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl); > bool kvm_require_dr(struct kvm_vcpu *vcpu, int dr); > > static inline int __kvm_irq_line_state(unsigned long *irq_state, > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index e69156b54cff..1c95d1fa3ead 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -2161,9 +2161,10 @@ int kvm_emulate_cpuid(struct kvm_vcpu *vcpu) > { > u32 eax, ebx, ecx, edx; > > - if (!is_smm(vcpu) && cpuid_fault_enabled(vcpu) && > - !kvm_require_cpl(vcpu, 0)) > + if (!kvm_is_cpuid_allowed(vcpu)) { > + kvm_queue_exception_e(vcpu, GP_VECTOR, 0); > return 1; > + } That's so much better! Will you drop this in when applying, or should I send a V3? ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 2/3] KVM: x86: Virtualize AMD CPUID faulting 2026-05-13 0:01 ` Jim Mattson @ 2026-05-13 0:04 ` Sean Christopherson 0 siblings, 0 replies; 7+ messages in thread From: Sean Christopherson @ 2026-05-13 0:04 UTC (permalink / raw) To: Jim Mattson Cc: Paolo Bonzini, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin, Shuah Khan, kvm, linux-kernel, linux-kselftest, Clayton Pence On Tue, May 12, 2026, Jim Mattson wrote: > On Tue, May 12, 2026 at 2:33 PM Sean Christopherson <seanjc@google.com> wrote: > > From: Sean Christopherson <seanjc@google.com> > > Date: Tue, 12 May 2026 14:20:47 -0700 > > Subject: [PATCH 1/3] KVM: x86: Consolidate CPUID fault handling for emulator > > and interception logic > > > > Extract the logic for emulating CPUID faulting (where CPUID #GPs at CPL>0 > > outside of SMM) into a dedicated helper and use the helper for both the > > full emulator and the intercepted-CPUID paths. > > > > Opportunistically drop kvm_require_cpl(), as kvm_require_cpl() was the one > > and only user. > > > > No functional change intended. > > > > Signed-off-by: Sean Christopherson <seanjc@google.com> > > --- > > arch/x86/include/asm/kvm_host.h | 1 - > > arch/x86/kvm/cpuid.c | 5 +++-- > > arch/x86/kvm/cpuid.h | 8 ++++++++ > > arch/x86/kvm/emulate.c | 6 +----- > > arch/x86/kvm/kvm_emulate.h | 1 + > > arch/x86/kvm/x86.c | 18 ++++++------------ > > 6 files changed, 19 insertions(+), 20 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index c470e40a00aa..a9005c61619b 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -2285,7 +2285,6 @@ void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned int nr, > > void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault); > > void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu, > > struct x86_exception *fault); > > -bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl); > > bool kvm_require_dr(struct kvm_vcpu *vcpu, int dr); > > > > static inline int __kvm_irq_line_state(unsigned long *irq_state, > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > > index e69156b54cff..1c95d1fa3ead 100644 > > --- a/arch/x86/kvm/cpuid.c > > +++ b/arch/x86/kvm/cpuid.c > > @@ -2161,9 +2161,10 @@ int kvm_emulate_cpuid(struct kvm_vcpu *vcpu) > > { > > u32 eax, ebx, ecx, edx; > > > > - if (!is_smm(vcpu) && cpuid_fault_enabled(vcpu) && > > - !kvm_require_cpl(vcpu, 0)) > > + if (!kvm_is_cpuid_allowed(vcpu)) { > > + kvm_queue_exception_e(vcpu, GP_VECTOR, 0); > > return 1; > > + } > > That's so much better! > > Will you drop this in when applying, or should I send a V3? Go ahead and send a v3. It slots in easy enough, but I'm trying not to get into the habit of applying pseudo-posted patches. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 3/3] KVM: selftests: Update hwcr_msr_test for CPUID faulting bit 2026-05-08 17:07 [PATCH v2 0/3] KVM: x86: Virtualize AMD CPUID faulting Jim Mattson 2026-05-08 17:07 ` [PATCH v2 1/3] KVM: x86: Remove supports_cpuid_fault() helper Jim Mattson 2026-05-08 17:07 ` [PATCH v2 2/3] KVM: x86: Virtualize AMD CPUID faulting Jim Mattson @ 2026-05-08 17:07 ` Jim Mattson 2 siblings, 0 replies; 7+ messages in thread From: Jim Mattson @ 2026-05-08 17:07 UTC (permalink / raw) To: Sean Christopherson, Paolo Bonzini, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86, H. Peter Anvin, Shuah Khan, kvm, linux-kernel, linux-kselftest, Clayton Pence Cc: Jim Mattson Add BIT_ULL(35) (CpuidUserDis) to the valid mask in hwcr_msr_test, now that KVM accepts writes to this bit when the guest CPUID advertises CpuidUserDis. Signed-off-by: Jim Mattson <jmattson@google.com> --- tools/testing/selftests/kvm/x86/hwcr_msr_test.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/tools/testing/selftests/kvm/x86/hwcr_msr_test.c b/tools/testing/selftests/kvm/x86/hwcr_msr_test.c index 8e20a03b3329..5357281e6e4e 100644 --- a/tools/testing/selftests/kvm/x86/hwcr_msr_test.c +++ b/tools/testing/selftests/kvm/x86/hwcr_msr_test.c @@ -10,11 +10,11 @@ void test_hwcr_bit(struct kvm_vcpu *vcpu, unsigned int bit) { - const u64 ignored = BIT_ULL(3) | BIT_ULL(6) | BIT_ULL(8); - const u64 valid = BIT_ULL(18) | BIT_ULL(24); - const u64 legal = ignored | valid; - u64 val = BIT_ULL(bit); - u64 actual; + const uint64_t ignored = BIT_ULL(3) | BIT_ULL(6) | BIT_ULL(8); + const uint64_t valid = BIT_ULL(18) | BIT_ULL(24) | BIT_ULL(35); + const uint64_t legal = ignored | valid; + uint64_t val = BIT_ULL(bit); + uint64_t actual; int r; r = _vcpu_set_msr(vcpu, MSR_K7_HWCR, val); -- 2.54.0.563.g4f69b47b94-goog ^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2026-05-13 0:04 UTC | newest] Thread overview: 7+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2026-05-08 17:07 [PATCH v2 0/3] KVM: x86: Virtualize AMD CPUID faulting Jim Mattson 2026-05-08 17:07 ` [PATCH v2 1/3] KVM: x86: Remove supports_cpuid_fault() helper Jim Mattson 2026-05-08 17:07 ` [PATCH v2 2/3] KVM: x86: Virtualize AMD CPUID faulting Jim Mattson 2026-05-12 21:33 ` Sean Christopherson 2026-05-13 0:01 ` Jim Mattson 2026-05-13 0:04 ` Sean Christopherson 2026-05-08 17:07 ` [PATCH v2 3/3] KVM: selftests: Update hwcr_msr_test for CPUID faulting bit Jim Mattson
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