@@ -523,6 +523,9 @@
#define MSR_RELOAD_PMC0 0x000014c1
#define MSR_RELOAD_FIXED_CTR0 0x00001309
+/* KeyID partitioning between MKTME and TDX */
+#define MSR_IA32_MKTME_KEYID_PARTITIONING 0x00000087
+
/*
* AMD64 MSRs. Not complete. See the architecture manual for a more
* complete list.
@@ -81,6 +81,10 @@ static inline long tdx_kvm_hypercall(unsigned int nr, unsigned long p1,
u64 __seamcall(u64 fn, struct tdx_module_args *args);
u64 __seamcall_ret(u64 fn, struct tdx_module_args *args);
u64 __seamcall_saved_ret(u64 fn, struct tdx_module_args *args);
+
+bool platform_tdx_enabled(void);
+#else
+static inline bool platform_tdx_enabled(void) { return false; }
#endif /* CONFIG_INTEL_TDX_HOST */
#endif /* !__ASSEMBLY__ */
@@ -1,2 +1,2 @@
# SPDX-License-Identifier: GPL-2.0-only
-obj-y += seamcall.o
+obj-y += seamcall.o tdx.o
new file mode 100644
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright(c) 2023 Intel Corporation.
+ *
+ * Intel Trusted Domain Extensions (TDX) support
+ */
+
+#define pr_fmt(fmt) "tdx: " fmt
+
+#include <linux/types.h>
+#include <linux/cache.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/printk.h>
+#include <asm/msr-index.h>
+#include <asm/msr.h>
+#include <asm/tdx.h>
+
+static u32 tdx_global_keyid __ro_after_init;
+static u32 tdx_guest_keyid_start __ro_after_init;
+static u32 tdx_nr_guest_keyids __ro_after_init;
+
+static int __init record_keyid_partitioning(u32 *tdx_keyid_start,
+ u32 *nr_tdx_keyids)
+{
+ u32 _nr_mktme_keyids, _tdx_keyid_start, _nr_tdx_keyids;
+ int ret;
+
+ /*
+ * IA32_MKTME_KEYID_PARTIONING:
+ * Bit [31:0]: Number of MKTME KeyIDs.
+ * Bit [63:32]: Number of TDX private KeyIDs.
+ */
+ ret = rdmsr_safe(MSR_IA32_MKTME_KEYID_PARTITIONING, &_nr_mktme_keyids,
+ &_nr_tdx_keyids);
+ if (ret)
+ return -ENODEV;
+
+ if (!_nr_tdx_keyids)
+ return -ENODEV;
+
+ /* TDX KeyIDs start after the last MKTME KeyID. */
+ _tdx_keyid_start = _nr_mktme_keyids + 1;
+
+ *tdx_keyid_start = _tdx_keyid_start;
+ *nr_tdx_keyids = _nr_tdx_keyids;
+
+ return 0;
+}
+
+static int __init tdx_init(void)
+{
+ u32 tdx_keyid_start, nr_tdx_keyids;
+ int err;
+
+ err = record_keyid_partitioning(&tdx_keyid_start, &nr_tdx_keyids);
+ if (err)
+ return err;
+
+ pr_info("BIOS enabled: private KeyID range [%u, %u)\n",
+ tdx_keyid_start, tdx_keyid_start + nr_tdx_keyids);
+
+ /*
+ * The TDX module itself requires one 'global KeyID' to protect
+ * its metadata. If there's only one TDX KeyID, there won't be
+ * any left for TDX guests thus there's no point to enable TDX
+ * at all.
+ */
+ if (nr_tdx_keyids < 2) {
+ pr_err("initialization failed: too few private KeyIDs available.\n");
+ return -ENODEV;
+ }
+
+ /*
+ * Just use the first TDX KeyID as the 'global KeyID' and
+ * leave the rest for TDX guests.
+ */
+ tdx_global_keyid = tdx_keyid_start;
+ tdx_guest_keyid_start = tdx_keyid_start + 1;
+ tdx_nr_guest_keyids = nr_tdx_keyids - 1;
+
+ return 0;
+}
+early_initcall(tdx_init);
+
+/* Return whether the BIOS has enabled TDX */
+bool platform_tdx_enabled(void)
+{
+ return !!tdx_global_keyid;
+}