linux-kernel - [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32

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Message-Id: <20220117082631.86143-1-likexu@tencent.com>
Date:   Mon, 17 Jan 2022 16:26:31 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Wanpeng Li <wanpengli@...cent.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset

From: Like Xu <likexu@...cent.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@...cent.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;
 	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);
 
-- 
2.33.1