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Message-ID: <20250328171205.2029296-14-xin@zytor.com>
Date: Fri, 28 Mar 2025 10:11:59 -0700
From: "Xin Li (Intel)" <xin@...or.com>
To: pbonzini@...hat.com, seanjc@...gle.com, kvm@...r.kernel.org,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: corbet@....net, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
andrew.cooper3@...rix.com, luto@...nel.org, peterz@...radead.org,
chao.gao@...el.com, xin3.li@...el.com
Subject: [PATCH v4 13/19] KVM: x86: Mark CR4.FRED as not reserved
From: Xin Li <xin3.li@...el.com>
The CR4.FRED bit, i.e., CR4[32], is no longer a reserved bit when
guest cpu cap has FRED, i.e.,
1) All of FRED KVM support is in place.
2) Guest enumerates FRED.
Otherwise it is still a reserved bit.
Signed-off-by: Xin Li <xin3.li@...el.com>
Signed-off-by: Xin Li (Intel) <xin@...or.com>
Tested-by: Shan Kang <shan.kang@...el.com>
---
Change in v4:
* Rebase on top of "guest_cpu_cap".
Change in v3:
* Don't allow CR4.FRED=1 before all of FRED KVM support is in place
(Sean Christopherson).
---
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 f8b9834f2f37..e94924397230 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -138,7 +138,7 @@
| 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 13dbd87970db..24661b2ad3ad 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -617,6 +617,8 @@ static inline bool __kvm_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
__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; \
})
--
2.48.1
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