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-rw-r--r--arch/x86/coco/core.c140
1 files changed, 140 insertions, 0 deletions
diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c
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+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Confidential Computing Platform Capability checks
+ *
+ * Copyright (C) 2021 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@amd.com>
+ */
+
+#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)
+{
+ switch (attr) {
+ case CC_ATTR_GUEST_UNROLL_STRING_IO:
+ case CC_ATTR_HOTPLUG_DISABLED:
+ case CC_ATTR_GUEST_MEM_ENCRYPT:
+ case CC_ATTR_MEM_ENCRYPT:
+ return true;
+ default:
+ 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);
+
+ case CC_ATTR_GUEST_SEV_SNP:
+ return sev_status & MSR_AMD64_SEV_SNP_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)
+{
+ /*
+ * Both AMD and Intel use a bit in the page table to indicate
+ * encryption status of the page.
+ *
+ * - for AMD, bit *set* means the page is encrypted
+ * - for Intel *clear* means encrypted.
+ */
+ switch (vendor) {
+ case CC_VENDOR_AMD:
+ return val | cc_mask;
+ case CC_VENDOR_INTEL:
+ return val & ~cc_mask;
+ default:
+ return val;
+ }
+}
+
+u64 cc_mkdec(u64 val)
+{
+ /* See comment in cc_mkenc() */
+ switch (vendor) {
+ case CC_VENDOR_AMD:
+ return val & ~cc_mask;
+ case CC_VENDOR_INTEL:
+ 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;
+}