Messages in this thread Patch in this message | | | Date | Sat, 9 Mar 2024 19:56:11 -0800 | Subject | Re: [PATCH 4/4] x86/tdx: Enable ENUM_TOPOLOGY | From | Kuppuswamy Sathyanarayanan <> |
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On 3/9/24 1:02 PM, Kirill A. Shutemov wrote: > 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.
Is this issue only for TDX 1.0? What about TDX > 1.0?
> > 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.
I cant find the ENUM_TOPOLOGY in ABI spec (https://cdrdv2.intel.com/v1/dl/getContent/795381).
Can you point me to the correct document?
> > 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. > + */
Why are we overriding it in guest? Why can't this by done by TDX Module or QEMU during initialization?
> + 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
-- Sathyanarayanan Kuppuswamy Linux Kernel Developer
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