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x86/tdx: Enable CPU topology enumeration

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TDX 1.0 defines baseline behaviour of TDX guest platform. 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
topology. 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. 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>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Link: https://lore.kernel.org/all/20241104103803.195705-5-kirill.shutemov%40linux.intel.com
This commit is contained in:
Kirill A. Shutemov 2024-11-04 12:38:03 +02:00 • committed by Dave Hansen
parent f65aa0ad79
commit 7ae15e2f69
2 changed files with 29 additions and 0 deletions
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27
arch/x86/coco/tdx/tdx.c
View file

@ -248,6 +248,32 @@ static void disable_sept_ve(u64 td_attr)
TD_CTLS_PENDING_VE_DISABLE);
}
/*
* 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.
* 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.
*/
static void enable_cpu_topology_enumeration(void)
{
u64 configured;
/* Has the VMM provided a valid topology configuration? */
tdg_vm_rd(TDCS_TOPOLOGY_ENUM_CONFIGURED, &configured);
if (!configured) {
pr_err("VMM did not configure X2APIC_IDs properly\n");
return;
}
tdg_vm_wr(TDCS_TD_CTLS, TD_CTLS_ENUM_TOPOLOGY, TD_CTLS_ENUM_TOPOLOGY);
}
static void tdx_setup(u64 *cc_mask)
{
struct tdx_module_args args = {};
@ -279,6 +305,7 @@ static void tdx_setup(u64 *cc_mask)
tdg_vm_wr(TDCS_NOTIFY_ENABLES, 0, -1ULL);
disable_sept_ve(td_attr);
enable_cpu_topology_enumeration();
}
/*

2
arch/x86/include/asm/shared/tdx.h
View file

@ -23,12 +23,14 @@
#define TDCS_CONFIG_FLAGS 0x1110000300000016
#define TDCS_TD_CTLS 0x1110000300000017
#define TDCS_NOTIFY_ENABLES 0x9100000000000010
#define TDCS_TOPOLOGY_ENUM_CONFIGURED 0x9100000000000019
/* 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