Message ID | 20220117082631.86143-1-likexu@tencent.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset | expand |
On 1/17/22 09:26, Like Xu wrote: > From: Like Xu <likexu@tencent.com> > > XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by > both RESET and INIT. In both cases, the size in bytes of the XSAVE > area containing all states enabled by XCR0 or (XCRO | IA32_XSS) > needs to be updated. > > Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT") > Signed-off-by: Like Xu <likexu@tencent.com> Can you write a test case please? Thanks, Paolo > --- > arch/x86/kvm/x86.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 76b4803dd3bd..5748a57e1cb7 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -11134,6 +11134,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > struct kvm_cpuid_entry2 *cpuid_0x1; > unsigned long old_cr0 = kvm_read_cr0(vcpu); > unsigned long new_cr0; > + bool need_update_cpuid = false; > > /* > * Several of the "set" flows, e.g. ->set_cr0(), read other registers > @@ -11199,6 +11200,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > > vcpu->arch.msr_misc_features_enables = 0; > > + if (vcpu->arch.xcr0 != XFEATURE_MASK_FP) > + need_update_cpuid = true; > vcpu->arch.xcr0 = XFEATURE_MASK_FP; > } > > @@ -11216,6 +11219,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0); > kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600); > > + if (vcpu->arch.ia32_xss) > + need_update_cpuid = true; > vcpu->arch.ia32_xss = 0; > > static_call(kvm_x86_vcpu_reset)(vcpu, init_event); > @@ -11264,6 +11269,9 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > */ > if (init_event) > kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu); > + > + if (need_update_cpuid) > + kvm_update_cpuid_runtime(vcpu); > } > EXPORT_SYMBOL_GPL(kvm_vcpu_reset); >
On Mon, Jan 17, 2022, Like Xu wrote: > From: Like Xu <likexu@tencent.com> > > XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by > both RESET and INIT. In both cases, the size in bytes of the XSAVE > area containing all states enabled by XCR0 or (XCRO | IA32_XSS) > needs to be updated. > > Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT") > Signed-off-by: Like Xu <likexu@tencent.com> > --- > arch/x86/kvm/x86.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 76b4803dd3bd..5748a57e1cb7 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -11134,6 +11134,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > struct kvm_cpuid_entry2 *cpuid_0x1; > unsigned long old_cr0 = kvm_read_cr0(vcpu); > unsigned long new_cr0; > + bool need_update_cpuid = false; > > /* > * Several of the "set" flows, e.g. ->set_cr0(), read other registers > @@ -11199,6 +11200,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > > vcpu->arch.msr_misc_features_enables = 0; > > + if (vcpu->arch.xcr0 != XFEATURE_MASK_FP) > + need_update_cpuid = true; > vcpu->arch.xcr0 = XFEATURE_MASK_FP; > } > > @@ -11216,6 +11219,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0); > kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600); > > + if (vcpu->arch.ia32_xss) > + need_update_cpuid = true; This means that kvm_set_msr_common()'s handling of MSR_IA32_XSS also needs to update kvm_update_cpuid_runtime(). And then for bnoth XCR0 and XSS, I would very strongly prefer that use the helpers to write the values and let the helpers call kvm_update_cpuid_runtime(). Yes, that will mean kvm_update_cpuid_runtime() may be called multiple times during INIT, but that's already true (CR4), and this isn't exactly a fast path. diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 55518b7d3b96..22d4b1d15e94 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11256,7 +11256,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) vcpu->arch.msr_misc_features_enables = 0; - vcpu->arch.xcr0 = XFEATURE_MASK_FP; + __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP); } /* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */ @@ -11273,7 +11273,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0); kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600); - vcpu->arch.ia32_xss = 0; + __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true); static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
On 19/1/2022 2:30 am, Sean Christopherson wrote: > On Mon, Jan 17, 2022, Like Xu wrote: >> From: Like Xu <likexu@tencent.com> >> >> XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by >> both RESET and INIT. In both cases, the size in bytes of the XSAVE >> area containing all states enabled by XCR0 or (XCRO | IA32_XSS) >> needs to be updated. >> >> Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT") >> Signed-off-by: Like Xu <likexu@tencent.com> >> --- >> arch/x86/kvm/x86.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 76b4803dd3bd..5748a57e1cb7 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -11134,6 +11134,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) >> struct kvm_cpuid_entry2 *cpuid_0x1; >> unsigned long old_cr0 = kvm_read_cr0(vcpu); >> unsigned long new_cr0; >> + bool need_update_cpuid = false; >> >> /* >> * Several of the "set" flows, e.g. ->set_cr0(), read other registers >> @@ -11199,6 +11200,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) >> >> vcpu->arch.msr_misc_features_enables = 0; >> >> + if (vcpu->arch.xcr0 != XFEATURE_MASK_FP) >> + need_update_cpuid = true; >> vcpu->arch.xcr0 = XFEATURE_MASK_FP; >> } >> >> @@ -11216,6 +11219,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) >> cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0); >> kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600); >> >> + if (vcpu->arch.ia32_xss) >> + need_update_cpuid = true; > > This means that kvm_set_msr_common()'s handling of MSR_IA32_XSS also needs to > update kvm_update_cpuid_runtime(). And then for bnoth XCR0 and XSS, I would very > strongly prefer that use the helpers to write the values and let the helpers call Looks good to me and let me apply it in the next version. > kvm_update_cpuid_runtime(). Yes, that will mean kvm_update_cpuid_runtime() may be > called multiple times during INIT, but that's already true (CR4), and this isn't > exactly a fast path. An undisclosed lazy mechanism is under analyzed for performance gains. > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 55518b7d3b96..22d4b1d15e94 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -11256,7 +11256,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > > vcpu->arch.msr_misc_features_enables = 0; > > - vcpu->arch.xcr0 = XFEATURE_MASK_FP; > + __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP); > } > > /* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */ > @@ -11273,7 +11273,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0); > kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600); > > - vcpu->arch.ia32_xss = 0; > + __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true); > > static_call(kvm_x86_vcpu_reset)(vcpu, init_event); > >
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 76b4803dd3bd..5748a57e1cb7 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11134,6 +11134,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) struct kvm_cpuid_entry2 *cpuid_0x1; unsigned long old_cr0 = kvm_read_cr0(vcpu); unsigned long new_cr0; + bool need_update_cpuid = false; /* * Several of the "set" flows, e.g. ->set_cr0(), read other registers @@ -11199,6 +11200,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) vcpu->arch.msr_misc_features_enables = 0; + if (vcpu->arch.xcr0 != XFEATURE_MASK_FP) + need_update_cpuid = true; vcpu->arch.xcr0 = XFEATURE_MASK_FP; } @@ -11216,6 +11219,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0); kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600); + if (vcpu->arch.ia32_xss) + need_update_cpuid = true; vcpu->arch.ia32_xss = 0; static_call(kvm_x86_vcpu_reset)(vcpu, init_event); @@ -11264,6 +11269,9 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) */ if (init_event) kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu); + + if (need_update_cpuid) + kvm_update_cpuid_runtime(vcpu); } EXPORT_SYMBOL_GPL(kvm_vcpu_reset);