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

Michael Kelley (LINUX)
2023-08-24T14:09:19Z

From: Dexuan Cui <decui@microsoft.com> 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@microsoft.com>
> ---
>
> 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@microsoft.com>