TDX 1.0 defines baseline behaviour of TDX guest platform. In 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. 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 | 32 +++++++++++++++++++++++++++++++
arch/x86/include/asm/shared/tdx.h | 3 +++
2 files changed, 35 insertions(+)
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 6124d86e0b1d..23c507fa4057 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -249,6 +249,36 @@ static int try_to_disable_sept_ve(u64 features0, u64 td_attr)
return 0;
}
+/*
+ * 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(u64 features0)
+{
+ u64 configured;
+
+ /* Does the TDX module support topology enumeration? */
+ if (!(features0 & TDX_FEATURES0_ENUM_TOPOLOGY))
+ return;
+
+ /* Has the VMM provided a valid topology configuration? */
+ if (tdg_vm_rd(TDCS_TOPOLOGY_ENUM_CONFIGURED, &configured) &&
+ 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 = {};
@@ -314,6 +344,8 @@ static void tdx_setup(u64 *cc_mask)
else
tdx_panic(msg);
}
+
+ enable_cpu_topology_enumeration(features0);
}
/*
diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index 282497d2964b..08a9ef35d04e 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
/* 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