linux-kernel - [PATCH 5.15 041/171] KVM: x86: Sync the states size with the XCR0/IA32

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Date:   Mon, 31 Jan 2022 11:55:06 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Like Xu <likexu@...cent.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 5.15 041/171] KVM: x86: Sync the states size with the XCR0/IA32_XSS at, any time

From: Like Xu <likexu@...cent.com>

commit 05a9e065059e566f218f8778c4d17ee75db56c55 upstream.

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")
Cc: stable@...r.kernel.org
Signed-off-by: Like Xu <likexu@...cent.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Message-Id: <20220126172226.2298529-4-seanjc@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/x86.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10990,8 +10990,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcp
 
 		vcpu->arch.msr_misc_features_enables = 0;
 
-		vcpu->arch.xcr0 = XFEATURE_MASK_FP;
-		vcpu->arch.ia32_xss = 0;
+		__kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
+		__kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
 	}
 
 	memset(vcpu->arch.regs, 0, sizeof(vcpu->arch.regs));