Messages in this thread | | | Date | Fri, 21 Jan 2022 15:41:53 +0000 | From | Sean Christopherson <> | Subject | Re: [PATCH v2] KVM: x86: Sync the states size with the XCR0/IA32_XSS at any time |
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On Fri, Jan 21, 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. The kvm_set_msr_common()'s handling of MSR_IA32_XSS > also needs to update kvm_update_cpuid_runtime(). In the above cases, the > size in bytes of the XSAVE area containing all states enabled by XCR0 or > (XCRO | IA32_XSS) needs to be updated. > > For simplicity and consistency, legacy helpers are used to write values
s/legacy/existing
"legacy" refers to something that is outdated/deprecated, which isn't what you intend here.
> and call kvm_update_cpuid_runtime(), and it's not exactly a fast path. > > Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT") > Signed-off-by: Like Xu <likexu@tencent.com> > --- > v1 -> v2 Changelog: > - Strongly prefer that use the helpers to write the values; (Sean) > - Postpone IA32_XSS test cases once non-zero values are supported; (Paolo) > - User space may call SET_CPUID2 after kvm_vcpu_reset(init_event=false); (Paolo) > > arch/x86/kvm/x86.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > 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);
This relies on a prep patch to invoke kvm_update_cpuid_runtime() in kvm_set_msr_common() for MSR_IA32_XSS, no?
> static_call(kvm_x86_vcpu_reset)(vcpu, init_event); > > -- > 2.33.1 > >
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