1 files changed, 117 insertions, 0 deletions
diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c
new file mode 100644
index 000000000000..fc1365dd927e
--- /dev/null
+++ b/arch/x86/coco/core.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Confidential Computing Platform Capability checks
+ *
+ * Copyright (C) 2021 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <[email protected]>
+ */
+
+#include <linux/export.h>
+#include <linux/cc_platform.h>
+
+#include <asm/coco.h>
+#include <asm/processor.h>
+
+static enum cc_vendor vendor __ro_after_init;
+static u64 cc_mask __ro_after_init;
+
+static bool intel_cc_platform_has(enum cc_attr attr)
+{
+	return false;
+}
+
+/*
+ * SME and SEV are very similar but they are not the same, so there are
+ * times that the kernel will need to distinguish between SME and SEV. The
+ * cc_platform_has() function is used for this.  When a distinction isn't
+ * needed, the CC_ATTR_MEM_ENCRYPT attribute can be used.
+ *
+ * The trampoline code is a good example for this requirement.  Before
+ * paging is activated, SME will access all memory as decrypted, but SEV
+ * will access all memory as encrypted.  So, when APs are being brought
+ * up under SME the trampoline area cannot be encrypted, whereas under SEV
+ * the trampoline area must be encrypted.
+ */
+static bool amd_cc_platform_has(enum cc_attr attr)
+{
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+	switch (attr) {
+	case CC_ATTR_MEM_ENCRYPT:
+		return sme_me_mask;
+
+	case CC_ATTR_HOST_MEM_ENCRYPT:
+		return sme_me_mask && !(sev_status & MSR_AMD64_SEV_ENABLED);
+
+	case CC_ATTR_GUEST_MEM_ENCRYPT:
+		return sev_status & MSR_AMD64_SEV_ENABLED;
+
+	case CC_ATTR_GUEST_STATE_ENCRYPT:
+		return sev_status & MSR_AMD64_SEV_ES_ENABLED;
+
+	/*
+	 * With SEV, the rep string I/O instructions need to be unrolled
+	 * but SEV-ES supports them through the #VC handler.
+	 */
+	case CC_ATTR_GUEST_UNROLL_STRING_IO:
+		return (sev_status & MSR_AMD64_SEV_ENABLED) &&
+			!(sev_status & MSR_AMD64_SEV_ES_ENABLED);
+
+	default:
+		return false;
+	}
+#else
+	return false;
+#endif
+}
+
+static bool hyperv_cc_platform_has(enum cc_attr attr)
+{
+	return attr == CC_ATTR_GUEST_MEM_ENCRYPT;
+}
+
+bool cc_platform_has(enum cc_attr attr)
+{
+	switch (vendor) {
+	case CC_VENDOR_AMD:
+		return amd_cc_platform_has(attr);
+	case CC_VENDOR_INTEL:
+		return intel_cc_platform_has(attr);
+	case CC_VENDOR_HYPERV:
+		return hyperv_cc_platform_has(attr);
+	default:
+		return false;
+	}
+}
+EXPORT_SYMBOL_GPL(cc_platform_has);
+
+u64 cc_mkenc(u64 val)
+{
+	switch (vendor) {
+	case CC_VENDOR_AMD:
+		return val | cc_mask;
+	default:
+		return val;
+	}
+}
+
+u64 cc_mkdec(u64 val)
+{
+	switch (vendor) {
+	case CC_VENDOR_AMD:
+		return val & ~cc_mask;
+	default:
+		return val;
+	}
+}
+EXPORT_SYMBOL_GPL(cc_mkdec);
+
+__init void cc_set_vendor(enum cc_vendor v)
+{
+	vendor = v;
+}
+
+__init void cc_set_mask(u64 mask)
+{
+	cc_mask = mask;
+}