From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: [PATCHv4 4/4] x86/tdx: Enable CPU topology enumeration
Date: Sun, 12 May 2024 15:21:54 +0300 [thread overview]
Message-ID: <20240512122154.2655269-5-kirill.shutemov@linux.intel.com> (raw)
In-Reply-To: <20240512122154.2655269-1-kirill.shutemov@linux.intel.com>
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. 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>
---
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 ba37f4306f4e..53d0b9df5a7f 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -249,6 +249,32 @@ static void disable_sept_ve(u64 td_attr)
return;
}
+/*
+ * 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 = {};
@@ -280,6 +306,7 @@ 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 fecb2a6e864b..89f7fcade8ae 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
--
2.43.0
prev parent reply other threads:[~2024-05-12 12:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-12 12:21 [PATCHv4 0/4] x86/tdx: Adjust TD settings on boot Kirill A. Shutemov
2024-05-12 12:21 ` [PATCHv4 1/4] x86/tdx: Factor out TD metadata write TDCALL Kirill A. Shutemov
2024-05-12 12:21 ` [PATCHv4 2/4] x86/tdx: Rename tdx_parse_tdinfo() to tdx_setup() Kirill A. Shutemov
2024-05-12 12:21 ` [PATCHv4 3/4] x86/tdx: Dynamically disable SEPT violations from causing #VEs Kirill A. Shutemov
2024-05-14 14:56 ` Nikolay Borisov
2024-05-15 9:30 ` Kirill A. Shutemov
2024-05-15 13:14 ` Nikolay Borisov
2024-05-15 13:22 ` Kirill A. Shutemov
2024-05-15 13:53 ` Dave Hansen
2024-05-12 12:21 ` Kirill A. Shutemov [this message]
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