Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | "Kirill A. Shutemov" <> | Subject | [PATCH 4/4] x86/tdx: Enable ENUM_TOPOLOGY | Date | Sat, 9 Mar 2024 23:02:30 +0200 |
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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.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> --- arch/x86/coco/tdx/tdx.c | 20 ++++++++++++++++++++ arch/x86/include/asm/shared/tdx.h | 3 +++ 2 files changed, 23 insertions(+)
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index d9ea82f8772d..291e45db8d54 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -280,6 +280,26 @@ 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)) { + tdg_vm_wr(TDCS_TD_CTLS, + TD_CTLS_ENUM_TOPOLOGY, + TD_CTLS_ENUM_TOPOLOGY); + } } /* 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 /* TDCS_TDX_FEATURES0 bits */ #define TDX_FEATURES0_PENDING_EPT_VIOLATION_V2 BIT_ULL(16) +#define TDX_FEATURES0_ENUM_TOPOLOGY BIT_ULL(20) /* TDCS_CONFIG_FLAGS bits */ #define TDCS_CONFIG_FLEXIBLE_PENDING_VE BIT_ULL(1) /* TDCS_TD_CTLS bits */ #define TD_CTLS_PENDING_VE_DISABLE BIT_ULL(0) +#define TD_CTLS_ENUM_TOPOLOGY BIT_ULL(1) /* TDX hypercall Leaf IDs */ #define TDVMCALL_MAP_GPA 0x10001 -- 2.43.0
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