linux-kernel - [PATCH 5.10 30/49] KVM: x86: Supplement __cr4_reserved_bits() with X86_FEATURE

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Message-Id: <20210310132322.895507927@linuxfoundation.org>
Date:   Wed, 10 Mar 2021 14:23:41 +0100
From:   gregkh@...uxfoundation.org
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 30/49] KVM: x86: Supplement __cr4_reserved_bits() with X86_FEATURE_PCID check

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

[ Upstream commit 4683d758f48e6ae87d3d3493ffa00aceb955ee16 ]

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@...hat.com>
Message-Id: <20210201142843.108190-1-vkuznets@...hat.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 e7ca622a468f..2249a7d7ca27 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -404,6 +404,8 @@ 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;                                \
 })
 
-- 
2.30.1