From: Xin Li <xin3.li@xxxxxxxxx>
The CR4.FRED bit, i.e., CR4[32], is no longer a reserved bit when
guest can use 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@xxxxxxxxx>
Signed-off-by: Xin Li (Intel) <xin@xxxxxxxxx>
Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
---
Changes since v2:
* 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/vmx/vmx.c | 4 ++++
arch/x86/kvm/x86.h | 2 ++
3 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3830084b569b..87f9f0b6cf3c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -136,7 +136,7 @@
| 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/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 03f42b218554..bfdd10773136 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8009,6 +8009,10 @@ void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_LAM);
kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_FRED);
+ /* Don't allow CR4.FRED=1 before all of FRED KVM support is in place. */
+ if (!guest_can_use(vcpu, X86_FEATURE_FRED))
+ vcpu->arch.cr4_guest_rsvd_bits |= X86_CR4_FRED;
+
vmx_setup_uret_msrs(vmx);
if (cpu_has_secondary_exec_ctrls())
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 992e73ee2ec5..0ed91512b757 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -561,6 +561,8 @@ enum kvm_msr_access {
__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; \
})
--
2.46.2
