Messages in this thread | | | Date | Wed, 26 Jan 2022 18:08:40 +0100 | Subject | Re: [PATCH v3] KVM: x86: Sync the states size with the XCR0/IA32_XSS at, any time | From | Paolo Bonzini <> |
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On 1/26/22 17:37, Sean Christopherson wrote: > On Sun, Jan 23, 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, existing helpers are used to write values >> 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> >> --- >> v2 -> v3 Changelog: >> - Apply s/legacy/existing in the commit message; (Sean) >> - Invoke kvm_update_cpuid_runtime() for MSR_IA32_XSS; (Sean) >> >> arch/x86/kvm/x86.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 55518b7d3b96..4b509b26d9ab 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -3535,6 +3535,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct >> msr_data *msr_info) >> if (data & ~supported_xss) >> return 1; >> vcpu->arch.ia32_xss = data; >> + kvm_update_cpuid_runtime(vcpu); >> break; >> case MSR_SMI_COUNT: >> if (!msr_info->host_initiated) >> @@ -11256,7 +11257,7 @@ 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 +11274,7 @@ 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); > > Heh, this now conflicts with a patch Xiaoyao just posted, turns out the SDM was > wrong. I think there's also some whitespace change or something that prevents > this from applying cleanly. For convenience, I'll post a miniseries with this > and Xiaoyao's patch. > > [*] https://lore.kernel.org/all/20220126034750.2495371-1-xiaoyao.li@intel.com
It's okay, fixing the conflict in Xiaoyao's patch is trivial and---anyway---KVM does not support XSS != 0 for now so his patch doesn't really have any practical effect.
Like's patch queued, thanks.
Paolo
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