linux-kernel - [PATCH 5.10 66/99] KVM: x86: Drop guest CPUID check for host initiated writes to MSR_IA32_PERF

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Date:   Mon, 20 Dec 2021 15:34:39 +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, Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 66/99] KVM: x86: Drop guest CPUID check for host initiated writes to MSR_IA32_PERF_CAPABILITIES

From: Vitaly Kuznetsov <vkuznets@...hat.com>

[ Upstream commit 1aa2abb33a419090c7c87d4ae842a6347078ee12 ]

The ability to write to MSR_IA32_PERF_CAPABILITIES from the host should
not depend on guest visible CPUID entries, even if just to allow
creating/restoring guest MSRs and CPUIDs in any sequence.

Fixes: 27461da31089 ("KVM: x86/pmu: Support full width counting")
Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Message-Id: <20211216165213.338923-3-vkuznets@...hat.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b885063dc393f..4f828cac0273e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3065,7 +3065,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 
 		if (!msr_info->host_initiated)
 			return 1;
-		if (guest_cpuid_has(vcpu, X86_FEATURE_PDCM) && kvm_get_msr_feature(&msr_ent))
+		if (kvm_get_msr_feature(&msr_ent))
 			return 1;
 		if (data & ~msr_ent.data)
 			return 1;
-- 
2.34.1