Re: [PATCHv2 4/4] x86/tdx: Enable ENUM_TOPOLOGY

Huang, Kai
2024-03-26T10:59:44Z

On Mon, 2024-03-25 at 12:46 +0200, Kirill A. Shutemov wrote:
> TDX 1.0 defines baseline behaviour of TDX guest platform. In TDX 1.0

^ Not needed.

> generates a #VE when accessing topology-related CPUID leafs (0xB and
> 0x1F) and the X2APIC_APICID MSR. The kernel returns all zeros on CPUID
> topology. Any complications will cause problems.
>
> The ENUM_TOPOLOGY feature allows the VMM to provide topology
> information to the guest. Enabling the feature eliminates
> topology-related #VEs: the TDX module virtualizes accesses to
> the CPUID leafs and the MSR.
>
> Enable ENUM_TOPOLOGY if it is available.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
> arch/x86/coco/tdx/tdx.c | 19 +++++++++++++++++++
> arch/x86/include/asm/shared/tdx.h | 3 +++
> 2 files changed, 22 insertions(+)
>
> diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
> index 860bfdd5a11d..b2d969432a22 100644
> --- a/arch/x86/coco/tdx/tdx.c
> +++ b/arch/x86/coco/tdx/tdx.c
> @@ -289,6 +289,25 @@ static void tdx_setup(u64 *cc_mask)
> else
> tdx_panic(msg);
> }
> +
> + /*
> + * TDX 1.0 generates a #VE when accessing topology-related CPUID leafs
> + * (0xB and 0x1F) and the X2APIC_APICID MSR. The kernel returns all
> + * zeros on CPUID #VEs. In practice, this means that the kernel can only
> + * boot with a plain topology. Any complications will cause problems.
> + *
> + * The ENUM_TOPOLOGY feature allows the VMM to provide topology
> + * information to the guest in a safe manner. Enabling the feature
> + * eliminates topology-related #VEs: the TDX module virtualizes
> + * accesses to the CPUID leafs and the MSR.
> + *
> + * Enable ENUM_TOPOLOGY if it is available.
> + */
> + if ((features & TDX_FEATURES0_ENUM_TOPOLOGY) &&
> + tdg_vm_rd(TDCS_TOPOLOGY_ENUM_CONFIGURED)) {
> + if (!tdcs_ctls_set(TD_CTLS_ENUM_TOPOLOGY))
> + pr_warn("Failed to enable ENUM_TOPOLOGY\n");
> + }
> }
>
> /*
> diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
> index 29a61c72e4dd..2964c506b241 100644
> --- a/arch/x86/include/asm/shared/tdx.h
> +++ b/arch/x86/include/asm/shared/tdx.h
> @@ -27,15 +27,18 @@
> #define TDCS_CONFIG_FLAGS 0x1110000300000016
> #define TDCS_TD_CTLS 0x1110000300000017
> #define TDCS_NOTIFY_ENABLES 0x9100000000000010
> +#define TDCS_TOPOLOGY_ENUM_CONFIGURED 0x9100000000000019

Do you know where can I find the metadata field ID definition?

It seems I couldn't find all metadata field ID definitions in the latest TDX 1.5
ABI spec anymore.