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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>
Subject: [PATCH] KVM: x86: Supplement __cr4_reserved_bits() with X86_FEATURE_PCID check
Date: Mon,  1 Feb 2021 15:28:43 +0100	[thread overview]
Message-ID: <20210201142843.108190-1-vkuznets@redhat.com> (raw)

Commit 7a873e455567 ("KVM: selftests: Verify supported CR4 bits can be set
before KVM_SET_CPUID2") reveals that KVM allows to set X86_CR4_PCIDE even
when PCID support is missing:

==== Test Assertion Failure ====
  x86_64/set_sregs_test.c:41: rc
  pid=6956 tid=6956 - Invalid argument
     1	0x000000000040177d: test_cr4_feature_bit at set_sregs_test.c:41
     2	0x00000000004014fc: main at set_sregs_test.c:119
     3	0x00007f2d9346d041: ?? ??:0
     4	0x000000000040164d: _start at ??:?
  KVM allowed unsupported CR4 bit (0x20000)

Add X86_FEATURE_PCID feature check to __cr4_reserved_bits() to make
kvm_is_valid_cr4() fail.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kvm/x86.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index c5ee0f5ce0f1..0f727b50bd3d 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -425,6 +425,8 @@ bool kvm_msr_allowed(struct kvm_vcpu *vcpu, u32 index, u32 type);
 		__reserved_bits |= X86_CR4_UMIP;        \
 	if (!__cpu_has(__c, X86_FEATURE_VMX))           \
 		__reserved_bits |= X86_CR4_VMXE;        \
+	if (!__cpu_has(__c, X86_FEATURE_PCID))          \
+		__reserved_bits |= X86_CR4_PCIDE;       \
 	__reserved_bits;                                \
 })
 
-- 
2.29.2


             reply	other threads:[~2021-02-01 14:30 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-01 14:28 Vitaly Kuznetsov [this message]
2021-02-01 14:43 ` [PATCH] KVM: x86: Supplement __cr4_reserved_bits() with X86_FEATURE_PCID check Paolo Bonzini

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