The following commit has been merged into the x86/tdx branch of tip:
Commit-ID: 7ae15e2f69bad06527668b478dff7c099ad2e6ae
Gitweb: https://git.kernel.org/tip/7ae15e2f69bad06527668b478dff7c099ad2e6ae
Author: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
AuthorDate: Mon, 04 Nov 2024 12:38:03 +02:00
Committer: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Thu, 07 Nov 2024 10:27:45 -08:00
x86/tdx: Enable CPU topology enumeration
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@xxxxxxxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Acked-by: Kai Huang <kai.huang@xxxxxxxxx>
Link: https://lore.kernel.org/all/20241104103803.195705-5-kirill.shutemov%40linux.intel.com
---
arch/x86/coco/tdx/tdx.c | 27 +++++++++++++++++++++++++++
arch/x86/include/asm/shared/tdx.h | 2 ++
2 files changed, 29 insertions(+)
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 2f85ed0..0d9b090 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -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();
}
/*
diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index fecb2a6..89f7fca 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -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
|