From: Sean Christopherson Date: Tue, 21 Sep 2021 00:02:58 +0000 (-0700) Subject: KVM: x86: Remove defunct setting of XCR0 for guest during vCPU create X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e8f65b9bb4832028cdbd5927ddb67f66c6ccdd27;p=linux.git KVM: x86: Remove defunct setting of XCR0 for guest during vCPU create Drop code to initialize XCR0 during fx_init(), a.k.a. vCPU creation, as XCR0 has been initialized during kvm_vcpu_reset() (for RESET) since commit a554d207dc46 ("KVM: X86: Processor States following Reset or INIT"). Back when XCR0 support was added by commit 2acf923e38fb ("KVM: VMX: Enable XSAVE/XRSTOR for guest"), KVM didn't differentiate between RESET and INIT. Ignoring the fact that calling fx_init() for INIT is obviously wrong, e.g. FPU state after INIT is not the same as after RESET, setting XCR0 in fx_init() was correct. Eventually fx_init() got moved to kvm_arch_vcpu_init(), a.k.a. vCPU creation (ignore the terrible name) by commit 0ee6a5172573 ("x86/fpu, kvm: Simplify fx_init()"). Finally, commit 95a0d01eef7a ("KVM: x86: Move all vcpu init code into kvm_arch_vcpu_create()") killed off kvm_arch_vcpu_init(), leaving behind the oddity of redundant setting of guest state during vCPU creation. No functional change intended. Signed-off-by: Sean Christopherson Reviewed-by: Vitaly Kuznetsov Signed-off-by: Paolo Bonzini Message-Id: <20210921000303.400537-6-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 69d6561251035..da0d48d107697 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -973,7 +973,7 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) /* * Do not allow the guest to set bits that we do not support * saving. However, xcr0 bit 0 is always set, even if the - * emulated CPU does not support XSAVE (see fx_init). + * emulated CPU does not support XSAVE (see kvm_vcpu_reset()). */ valid_bits = vcpu->arch.guest_supported_xcr0 | XFEATURE_MASK_FP; if (xcr0 & ~valid_bits) @@ -10606,11 +10606,6 @@ static void fx_init(struct kvm_vcpu *vcpu) if (boot_cpu_has(X86_FEATURE_XSAVES)) vcpu->arch.guest_fpu->state.xsave.header.xcomp_bv = host_xcr0 | XSTATE_COMPACTION_ENABLED; - - /* - * Ensure guest xcr0 is valid for loading - */ - vcpu->arch.xcr0 = XFEATURE_MASK_FP; } void kvm_free_guest_fpu(struct kvm_vcpu *vcpu)