1 files changed, 362 insertions, 0 deletions
diff --git a/arch/x86/coco/sev/svsm.c b/arch/x86/coco/sev/svsm.c
new file mode 100644
index 000000000000..2acf4a76afe7
--- /dev/null
+++ b/arch/x86/coco/sev/svsm.c
@@ -0,0 +1,362 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SVSM support code
+ */
+
+#include <linux/types.h>
+
+#include <asm/sev.h>
+
+#include "internal.h"
+
+/* For early boot SVSM communication */
+struct svsm_ca boot_svsm_ca_page __aligned(PAGE_SIZE);
+SYM_PIC_ALIAS(boot_svsm_ca_page);
+
+/*
+ * SVSM related information:
+ *   During boot, the page tables are set up as identity mapped and later
+ *   changed to use kernel virtual addresses. Maintain separate virtual and
+ *   physical addresses for the CAA to allow SVSM functions to be used during
+ *   early boot, both with identity mapped virtual addresses and proper kernel
+ *   virtual addresses.
+ */
+u64 boot_svsm_caa_pa __ro_after_init;
+SYM_PIC_ALIAS(boot_svsm_caa_pa);
+
+DEFINE_PER_CPU(struct svsm_ca *, svsm_caa);
+DEFINE_PER_CPU(u64, svsm_caa_pa);
+
+static int svsm_perform_ghcb_protocol(struct ghcb *ghcb, struct svsm_call *call)
+{
+	struct es_em_ctxt ctxt;
+	u8 pending = 0;
+
+	vc_ghcb_invalidate(ghcb);
+
+	/*
+	 * Fill in protocol and format specifiers. This can be called very early
+	 * in the boot, so use rip-relative references as needed.
+	 */
+	ghcb->protocol_version = ghcb_version;
+	ghcb->ghcb_usage       = GHCB_DEFAULT_USAGE;
+
+	ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_SNP_RUN_VMPL);
+	ghcb_set_sw_exit_info_1(ghcb, 0);
+	ghcb_set_sw_exit_info_2(ghcb, 0);
+
+	sev_es_wr_ghcb_msr(__pa(ghcb));
+
+	svsm_issue_call(call, &pending);
+
+	if (pending)
+		return -EINVAL;
+
+	switch (verify_exception_info(ghcb, &ctxt)) {
+	case ES_OK:
+		break;
+	case ES_EXCEPTION:
+		vc_forward_exception(&ctxt);
+		fallthrough;
+	default:
+		return -EINVAL;
+	}
+
+	return svsm_process_result_codes(call);
+}
+
+int svsm_perform_call_protocol(struct svsm_call *call)
+{
+	struct ghcb_state state;
+	unsigned long flags;
+	struct ghcb *ghcb;
+	int ret;
+
+	flags = native_local_irq_save();
+
+	if (sev_cfg.ghcbs_initialized)
+		ghcb = __sev_get_ghcb(&state);
+	else if (boot_ghcb)
+		ghcb = boot_ghcb;
+	else
+		ghcb = NULL;
+
+	do {
+		ret = ghcb ? svsm_perform_ghcb_protocol(ghcb, call)
+			   : __pi_svsm_perform_msr_protocol(call);
+	} while (ret == -EAGAIN);
+
+	if (sev_cfg.ghcbs_initialized)
+		__sev_put_ghcb(&state);
+
+	native_local_irq_restore(flags);
+
+	return ret;
+}
+
+static u64 svsm_build_ca_from_pfn_range(u64 pfn, u64 pfn_end, bool action,
+					struct svsm_pvalidate_call *pc)
+{
+	struct svsm_pvalidate_entry *pe;
+
+	/* Nothing in the CA yet */
+	pc->num_entries = 0;
+	pc->cur_index   = 0;
+
+	pe = &pc->entry[0];
+
+	while (pfn < pfn_end) {
+		pe->page_size = RMP_PG_SIZE_4K;
+		pe->action    = action;
+		pe->ignore_cf = 0;
+		pe->rsvd      = 0;
+		pe->pfn       = pfn;
+
+		pe++;
+		pfn++;
+
+		pc->num_entries++;
+		if (pc->num_entries == SVSM_PVALIDATE_MAX_COUNT)
+			break;
+	}
+
+	return pfn;
+}
+
+static int svsm_build_ca_from_psc_desc(struct snp_psc_desc *desc, unsigned int desc_entry,
+				       struct svsm_pvalidate_call *pc)
+{
+	struct svsm_pvalidate_entry *pe;
+	struct psc_entry *e;
+
+	/* Nothing in the CA yet */
+	pc->num_entries = 0;
+	pc->cur_index   = 0;
+
+	pe = &pc->entry[0];
+	e  = &desc->entries[desc_entry];
+
+	while (desc_entry <= desc->hdr.end_entry) {
+		pe->page_size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K;
+		pe->action    = e->operation == SNP_PAGE_STATE_PRIVATE;
+		pe->ignore_cf = 0;
+		pe->rsvd      = 0;
+		pe->pfn       = e->gfn;
+
+		pe++;
+		e++;
+
+		desc_entry++;
+		pc->num_entries++;
+		if (pc->num_entries == SVSM_PVALIDATE_MAX_COUNT)
+			break;
+	}
+
+	return desc_entry;
+}
+
+static void svsm_pval_terminate(struct svsm_pvalidate_call *pc, int ret, u64 svsm_ret)
+{
+	unsigned int page_size;
+	bool action;
+	u64 pfn;
+
+	pfn = pc->entry[pc->cur_index].pfn;
+	action = pc->entry[pc->cur_index].action;
+	page_size = pc->entry[pc->cur_index].page_size;
+
+	__pval_terminate(pfn, action, page_size, ret, svsm_ret);
+}
+
+void svsm_pval_pages(struct snp_psc_desc *desc)
+{
+	struct svsm_pvalidate_entry pv_4k[VMGEXIT_PSC_MAX_ENTRY];
+	unsigned int i, pv_4k_count = 0;
+	struct svsm_pvalidate_call *pc;
+	struct svsm_call call = {};
+	unsigned long flags;
+	bool action;
+	u64 pc_pa;
+	int ret;
+
+	/*
+	 * This can be called very early in the boot, use native functions in
+	 * order to avoid paravirt issues.
+	 */
+	flags = native_local_irq_save();
+
+	/*
+	 * The SVSM calling area (CA) can support processing 510 entries at a
+	 * time. Loop through the Page State Change descriptor until the CA is
+	 * full or the last entry in the descriptor is reached, at which time
+	 * the SVSM is invoked. This repeats until all entries in the descriptor
+	 * are processed.
+	 */
+	call.caa = svsm_get_caa();
+
+	pc = (struct svsm_pvalidate_call *)call.caa->svsm_buffer;
+	pc_pa = svsm_get_caa_pa() + offsetof(struct svsm_ca, svsm_buffer);
+
+	/* Protocol 0, Call ID 1 */
+	call.rax = SVSM_CORE_CALL(SVSM_CORE_PVALIDATE);
+	call.rcx = pc_pa;
+
+	for (i = 0; i <= desc->hdr.end_entry;) {
+		i = svsm_build_ca_from_psc_desc(desc, i, pc);
+
+		do {
+			ret = svsm_perform_call_protocol(&call);
+			if (!ret)
+				continue;
+
+			/*
+			 * Check if the entry failed because of an RMP mismatch (a
+			 * PVALIDATE at 2M was requested, but the page is mapped in
+			 * the RMP as 4K).
+			 */
+
+			if (call.rax_out == SVSM_PVALIDATE_FAIL_SIZEMISMATCH &&
+			    pc->entry[pc->cur_index].page_size == RMP_PG_SIZE_2M) {
+				/* Save this entry for post-processing at 4K */
+				pv_4k[pv_4k_count++] = pc->entry[pc->cur_index];
+
+				/* Skip to the next one unless at the end of the list */
+				pc->cur_index++;
+				if (pc->cur_index < pc->num_entries)
+					ret = -EAGAIN;
+				else
+					ret = 0;
+			}
+		} while (ret == -EAGAIN);
+
+		if (ret)
+			svsm_pval_terminate(pc, ret, call.rax_out);
+	}
+
+	/* Process any entries that failed to be validated at 2M and validate them at 4K */
+	for (i = 0; i < pv_4k_count; i++) {
+		u64 pfn, pfn_end;
+
+		action  = pv_4k[i].action;
+		pfn     = pv_4k[i].pfn;
+		pfn_end = pfn + 512;
+
+		while (pfn < pfn_end) {
+			pfn = svsm_build_ca_from_pfn_range(pfn, pfn_end, action, pc);
+
+			ret = svsm_perform_call_protocol(&call);
+			if (ret)
+				svsm_pval_terminate(pc, ret, call.rax_out);
+		}
+	}
+
+	native_local_irq_restore(flags);
+}
+
+static void update_attest_input(struct svsm_call *call, struct svsm_attest_call *input)
+{
+	/* If (new) lengths have been returned, propagate them up */
+	if (call->rcx_out != call->rcx)
+		input->manifest_buf.len = call->rcx_out;
+
+	if (call->rdx_out != call->rdx)
+		input->certificates_buf.len = call->rdx_out;
+
+	if (call->r8_out != call->r8)
+		input->report_buf.len = call->r8_out;
+}
+
+int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call,
+			      struct svsm_attest_call *input)
+{
+	struct svsm_attest_call *ac;
+	unsigned long flags;
+	u64 attest_call_pa;
+	int ret;
+
+	if (!snp_vmpl)
+		return -EINVAL;
+
+	local_irq_save(flags);
+
+	call->caa = svsm_get_caa();
+
+	ac = (struct svsm_attest_call *)call->caa->svsm_buffer;
+	attest_call_pa = svsm_get_caa_pa() + offsetof(struct svsm_ca, svsm_buffer);
+
+	*ac = *input;
+
+	/*
+	 * Set input registers for the request and set RDX and R8 to known
+	 * values in order to detect length values being returned in them.
+	 */
+	call->rax = call_id;
+	call->rcx = attest_call_pa;
+	call->rdx = -1;
+	call->r8 = -1;
+	ret = svsm_perform_call_protocol(call);
+	update_attest_input(call, input);
+
+	local_irq_restore(flags);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req);
+
+/**
+ * snp_svsm_vtpm_send_command() - Execute a vTPM operation on SVSM
+ * @buffer: A buffer used to both send the command and receive the response.
+ *
+ * Execute a SVSM_VTPM_CMD call as defined by
+ * "Secure VM Service Module for SEV-SNP Guests" Publication # 58019 Revision: 1.00
+ *
+ * All command request/response buffers have a common structure as specified by
+ * the following table:
+ *     Byte      Size       In/Out    Description
+ *     Offset    (Bytes)
+ *     0x000     4          In        Platform command
+ *                          Out       Platform command response size
+ *
+ * Each command can build upon this common request/response structure to create
+ * a structure specific to the command. See include/linux/tpm_svsm.h for more
+ * details.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int snp_svsm_vtpm_send_command(u8 *buffer)
+{
+	struct svsm_call call = {};
+
+	call.caa = svsm_get_caa();
+	call.rax = SVSM_VTPM_CALL(SVSM_VTPM_CMD);
+	call.rcx = __pa(buffer);
+
+	return svsm_perform_call_protocol(&call);
+}
+EXPORT_SYMBOL_GPL(snp_svsm_vtpm_send_command);
+
+/**
+ * snp_svsm_vtpm_probe() - Probe if SVSM provides a vTPM device
+ *
+ * Check that there is SVSM and that it supports at least TPM_SEND_COMMAND
+ * which is the only request used so far.
+ *
+ * Return: true if the platform provides a vTPM SVSM device, false otherwise.
+ */
+bool snp_svsm_vtpm_probe(void)
+{
+	struct svsm_call call = {};
+
+	/* The vTPM device is available only if a SVSM is present */
+	if (!snp_vmpl)
+		return false;
+
+	call.caa = svsm_get_caa();
+	call.rax = SVSM_VTPM_CALL(SVSM_VTPM_QUERY);
+
+	if (svsm_perform_call_protocol(&call))
+		return false;
+
+	/* Check platform commands contains TPM_SEND_COMMAND - platform command 8 */
+	return call.rcx_out & BIT_ULL(8);
+}