Re: [PATCH v6 5/9] KVM: VMX: Track CPU's MSR_IA32_VMX_BASIC as a single 64-bit value

Xiaoyao Li
2024-04-01T06:27:44Z

On 3/9/2024 9:27 AM, Sean Christopherson wrote:
> Track the "basic" capabilities VMX MSR as a single u64 in vmcs_config
> instead of splitting it across three fields, that obviously don't combine
> into a single 64-bit value, so that KVM can use the macros that define MSR
> bits using their absolute position. Replace all open coded shifts and
> masks, many of which are relative to the "high" half, with the appropriate
> macro.
>
> Opportunistically use VMX_BASIC_32BIT_PHYS_ADDR_ONLY instead of an open
> coded equivalent, and clean up the related comment to not reference a
> specific SDM section (to the surprise of no one, the comment is stale).
>
> No functional change intended (though obviously the code generation will
> be quite different).
>
> Cc: Shan Kang <shan.kang@intel.com>
> Cc: Kai Huang <kai.huang@intel.com>
> Signed-off-by: Xin Li <xin3.li@intel.com>
> [sean: split to separate patch, write changelog]

The patch author doesn't match with the signed-off

> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/include/asm/vmx.h | 5 +++++
> arch/x86/kvm/vmx/capabilities.h | 6 ++----
> arch/x86/kvm/vmx/vmx.c | 28 ++++++++++++++--------------
> 3 files changed, 21 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index c3a97dca4a33..ce6d166fc3c5 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -150,6 +150,11 @@ static inline u32 vmx_basic_vmcs_size(u64 vmx_basic)
> return (vmx_basic & GENMASK_ULL(44, 32)) >> 32;
> }
>
> +static inline u32 vmx_basic_vmcs_mem_type(u64 vmx_basic)
> +{
> + return (vmx_basic & GENMASK_ULL(53, 50)) >> 50;

#define VMX_BASIC_MEM_TYPE_SHIFT 50

We have the shift defined in previous patch, we need to use it I think,
Any maybe, we can define the MASK as well.

Otherwise, this cleanup is good.

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>