Re: [PATCH] KVM-Use value reading from MSR when construct the eptp in VMX mode

From: Dennis Chen
Date: Sun Aug 24 2014 - 00:20:20 EST


CC'ing Avi and Paolo...

Avi/Paolo, any comments? --Den

On Sun, Aug 24, 2014 at 11:54 AM, Dennis Chen <kernel.org.gnu@xxxxxxxxx> wrote:
> This patch is used to construct the eptp in vmx mode with values
> readed from MSR according to the intel x86 software developer's
> manual.
>
> Signed-off-by: Dennis Chen <kernel.org.gnu@xxxxxxxxx>
> ---
> arch/x86/include/asm/vmx.h | 1 +
> arch/x86/kvm/vmx.c | 21 +++++++++++++++++----
> 2 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index bcbfade..bf82a77 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -417,6 +417,7 @@ enum vmcs_field {
> #define VMX_EPT_GAW_EPTP_SHIFT 3
> #define VMX_EPT_AD_ENABLE_BIT (1ull << 6)
> #define VMX_EPT_DEFAULT_MT 0x6ull
> +#define VMX_EPT_UC_MT 0x0ull
> #define VMX_EPT_READABLE_MASK 0x1ull
> #define VMX_EPT_WRITABLE_MASK 0x2ull
> #define VMX_EPT_EXECUTABLE_MASK 0x4ull
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index bfe11cf..7add5ce 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3477,11 +3477,24 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu,
> unsigned long cr0)
>
> static u64 construct_eptp(unsigned long root_hpa)
> {
> - u64 eptp;
> + u64 eptp, pwl;
> +
> + if (cpu_has_vmx_ept_4levels())
> + pwl = VMX_EPT_DEFAULT_GAW << VMX_EPT_GAW_EPTP_SHIFT;
> + else {
> + WARN(1, "Unsupported page-walk length of 4.\n");
> + BUG();
> + }
> +
> + if (cpu_has_vmx_eptp_writeback())
> + eptp = VMX_EPT_DEFAULT_MT | pwl;
> + else if (cpu_has_vmx_eptp_uncacheable())
> + eptp = VMX_EPT_UC_MT | pwl;
> + else {
> + WARN(1, "Unsupported memory type config in vmx eptp.\n");
> + BUG();
> + }
>
> - /* TODO write the value reading from MSR */
> - eptp = VMX_EPT_DEFAULT_MT |
> - VMX_EPT_DEFAULT_GAW << VMX_EPT_GAW_EPTP_SHIFT;
> if (enable_ept_ad_bits)
> eptp |= VMX_EPT_AD_ENABLE_BIT;
> eptp |= (root_hpa & PAGE_MASK);
> --
> 1.7.9.5
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