RE: [PATCH v3 08/10] x86/hyperv: Use TDX GHCI to access some MSRs in a TDX VM with the paravisor

[Michael Kelley (LINUX)]

From: Dexuan Cui <decui@xxxxxxxxxxxxx> Sent: Thursday, August 24, 2023 1:07 AM
> 
> When the paravisor is present, a SNP VM must use GHCB to access some
> special MSRs, including HV_X64_MSR_GUEST_OS_ID and some SynIC MSRs.
> 
> Similarly, when the paravisor is present, a TDX VM must use TDX GHCI
> to access the same MSRs.
> 
> Implement hv_tdx_msr_write() and hv_tdx_msr_read(), and use the helper
> functions hv_ivm_msr_read() and hv_ivm_msr_write() to access the MSRs
> in a unified way for SNP/TDX VMs with the paravisor.
> 
> Do not export hv_tdx_msr_write() and hv_tdx_msr_read(), because we never
> really used hv_ghcb_msr_write() and hv_ghcb_msr_read() in any module.
> 
> Update arch/x86/include/asm/mshyperv.h so that the kernel can still build
> if CONFIG_AMD_MEM_ENCRYPT or CONFIG_INTEL_TDX_GUEST is not set, or
> neither is set.
> 
> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> ---
> 
> Changes in v2: None
> 
> Changes in v3:
>   hv_tdx_read_msr -> hv_tdx_msr_read
>   hv_tdx_write_msr -> hv_tdx_msr_write
>   Do not export hv_tdx_msr_write() and hv_tdx_msr_read().
>   included <uapi/asm/vmx.h>
>   Updated arch/x86/include/asm/mshyperv.h so that the kernel
>     can still build if CONFIG_AMD_MEM_ENCRYPT and/or
>     CONFIG_INTEL_TDX_GUEST are not set.
> 
>  arch/x86/hyperv/hv_init.c       |  8 ++--
>  arch/x86/hyperv/ivm.c           | 69 +++++++++++++++++++++++++++++++--
>  arch/x86/include/asm/mshyperv.h |  8 ++--
>  arch/x86/kernel/cpu/mshyperv.c  |  8 ++--
>  4 files changed, 77 insertions(+), 16 deletions(-)

Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>