Re: [PATCH V4 1/7] KVM, pkeys: expose CPUID/CR4 to guest

[Xiao Guangrong <guangrong.xiao@linux.intel.com>]

On 03/05/2016 07:27 PM, Huaitong Han wrote:
> X86_FEATURE_PKU is referred to as "PKU" in the hardware documentation:
> CPUID.7.0.ECX[3]:PKU. X86_FEATURE_OSPKE is software support for pkeys,
> enumerated with CPUID.7.0.ECX[4]:OSPKE, and it reflects the setting of
> CR4.PKE(bit 22).
>
> Signed-off-by: Huaitong Han <huaitong.han@intel.com>
> ---
>   arch/x86/include/asm/kvm_host.h |  3 ++-
>   arch/x86/kvm/cpuid.c            | 21 +++++++++++++++++++--
>   arch/x86/kvm/cpuid.h            |  8 ++++++++
>   arch/x86/kvm/x86.c              |  9 ++++++---
>   4 files changed, 35 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 44adbb8..2867626 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -83,7 +83,8 @@
>   			  | X86_CR4_PSE | X86_CR4_PAE | X86_CR4_MCE     \
>   			  | X86_CR4_PGE | X86_CR4_PCE | X86_CR4_OSFXSR | X86_CR4_PCIDE \
>   			  | X86_CR4_OSXSAVE | X86_CR4_SMEP | X86_CR4_FSGSBASE \
> -			  | X86_CR4_OSXMMEXCPT | X86_CR4_VMXE | X86_CR4_SMAP))
> +			  | X86_CR4_OSXMMEXCPT | X86_CR4_VMXE | X86_CR4_SMAP \
> +			  | X86_CR4_PKE))
>
>   #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 6525e92..f058db5 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -81,6 +81,17 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
>   			apic->lapic_timer.timer_mode_mask = 1 << 17;
>   	}
>
> +	best = kvm_find_cpuid_entry(vcpu, 7, 0);
> +	if (!best)
> +		return 0;
> +
> +	/*Update OSPKE bit */

Missed a space here.

> +	if (boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7) {
> +		best->ecx &= ~F(OSPKE);
> +		if (kvm_read_cr4_bits(vcpu, X86_CR4_PKE))
> +			best->ecx |= F(OSPKE);
> +	}
> +
>   	best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
>   	if (!best) {
>   		vcpu->arch.guest_supported_xcr0 = 0;
> @@ -354,6 +365,9 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
>   	const u32 kvm_supported_word10_x86_features =
>   		F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | f_xsaves;
>
> +	/* cpuid 7.0.ecx*/
> +	const u32 kvm_supported_word11_x86_features = F(PKU) | 0 /*OSPKE*/;
> +
>   	/* all calls to cpuid_count() should be made on the same cpu */
>   	get_cpu();
>
> @@ -431,10 +445,13 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
>   			cpuid_mask(&entry->ebx, 9);
>   			// TSC_ADJUST is emulated
>   			entry->ebx |= F(TSC_ADJUST);
> -		} else
> +			entry->ecx &= kvm_supported_word11_x86_features;
> +			cpuid_mask(&entry->ecx, 13);

Can we use a meaningful name defined by cpuid_leafs instead of the raw number?