linux-kernel - [PATCH v2 04/25] KVM: x86: Mark CR4.FRED as not reserved

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Date: Wed,  7 Feb 2024 09:26:24 -0800
From: Xin Li <xin3.li@...el.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Cc: seanjc@...gle.com,
	pbonzini@...hat.com,
	corbet@....net,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com,
	shuah@...nel.org,
	vkuznets@...hat.com,
	peterz@...radead.org,
	ravi.v.shankar@...el.com,
	xin@...or.com
Subject: [PATCH v2 04/25] KVM: x86: Mark CR4.FRED as not reserved

The CR4.FRED bit, i.e., CR4[32], is no longer a reserved bit when a guest
enumerates FRED, otherwise it is still a reserved bit.

Signed-off-by: Xin Li <xin3.li@...el.com>
Tested-by: Shan Kang <shan.kang@...el.com>
---
 arch/x86/include/asm/kvm_host.h | 2 +-
 arch/x86/kvm/x86.h              | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b5b2d0fde579..0d88873eba63 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -134,7 +134,7 @@
 			  | X86_CR4_OSXSAVE | X86_CR4_SMEP | X86_CR4_FSGSBASE \
 			  | X86_CR4_OSXMMEXCPT | X86_CR4_LA57 | X86_CR4_VMXE \
 			  | X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP \
-			  | X86_CR4_LAM_SUP))
+			  | X86_CR4_LAM_SUP | X86_CR4_FRED))
 
 #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
 
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 2f7e19166658..9a52016ebf5a 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -532,6 +532,8 @@ bool kvm_msr_allowed(struct kvm_vcpu *vcpu, u32 index, u32 type);
 		__reserved_bits |= X86_CR4_PCIDE;       \
 	if (!__cpu_has(__c, X86_FEATURE_LAM))           \
 		__reserved_bits |= X86_CR4_LAM_SUP;     \
+	if (!__cpu_has(__c, X86_FEATURE_FRED))          \
+		__reserved_bits |= X86_CR4_FRED;        \
 	__reserved_bits;                                \
 })
 
-- 
2.43.0