[RFC Part2 PATCH 09/30] crypto: ccp: Add support to initialize the AMD-SP for SEV-SNP

[Brijesh Singh]

Before SNP VMs can be launched, the platform must be appropriately
configured and initialized. Platform initialization is accomplished via
the SNP_INIT command.

Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Joerg Roedel <jroedel@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
 drivers/crypto/ccp/sev-dev.c | 164 ++++++++++++++++++++++++++++++++++-
 drivers/crypto/ccp/sev-dev.h |   2 +
 include/linux/psp-sev.h      |  16 ++++
 3 files changed, 179 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 8a9fd843ad9e..c983a8b040c3 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -21,8 +21,10 @@
 #include <linux/ccp.h>
 #include <linux/firmware.h>
 #include <linux/gfp.h>
+#include <linux/mem_encrypt.h>
 
 #include <asm/smp.h>
+#include <asm/sev-snp.h>
 
 #include "psp-dev.h"
 #include "sev-dev.h"
@@ -30,6 +32,7 @@
 #define DEVICE_NAME		"sev"
 #define SEV_FW_FILE		"amd/sev.fw"
 #define SEV_FW_NAME_SIZE	64
+#define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT)
 
 static DEFINE_MUTEX(sev_cmd_mutex);
 static struct sev_misc_dev *misc_dev;
@@ -574,6 +577,93 @@ static int sev_update_firmware(struct device *dev)
 	return ret;
 }
 
+static void snp_set_hsave_pa(void *arg)
+{
+	wrmsrl(MSR_VM_HSAVE_PA, 0);
+}
+
+static int __sev_snp_init_locked(int *error)
+{
+	struct psp_device *psp = psp_master;
+	struct sev_device *sev;
+	int rc = 0;
+
+	if (!psp || !psp->sev_data)
+		return -ENODEV;
+
+	sev = psp->sev_data;
+
+	if (sev->snp_inited && sev->state >= SEV_STATE_INIT)
+		return 0;
+
+	if (!snp_key_active()) {
+		dev_notice(sev->dev, "SNP is not enabled\n");
+		return -ENODEV;
+	}
+
+	/* SNP_INIT requires the MSR_VM_HSAVE_PA must be set to 0h across all cores. */
+	on_each_cpu(snp_set_hsave_pa, NULL, 1);
+
+	/* Prepare for first SEV guest launch after INIT */
+	wbinvd_on_all_cpus();
+
+	/* Issue the SNP_INIT firmware command. */
+	rc = __sev_do_cmd_locked(SEV_CMD_SNP_INIT, NULL, error);
+	if (rc)
+		return rc;
+
+	sev->snp_inited = true;
+	sev->state = SEV_STATE_INIT;
+	dev_dbg(sev->dev, "SEV-SNP firmware initialized\n");
+
+	return rc;
+}
+
+int sev_snp_init(int *error)
+{
+	int rc;
+
+	mutex_lock(&sev_cmd_mutex);
+	rc = __sev_snp_init_locked(error);
+	mutex_unlock(&sev_cmd_mutex);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(sev_snp_init);
+
+static int __sev_snp_shutdown_locked(int *error)
+{
+	struct sev_device *sev = psp_master->sev_data;
+	int ret;
+
+	ret = __sev_do_cmd_locked(SEV_CMD_SNP_SHUTDOWN, NULL, error);
+	if (ret)
+		return ret;
+
+	wbinvd_on_all_cpus();
+
+	ret = __sev_do_cmd_locked(SEV_CMD_SNP_DF_FLUSH, NULL, error);
+	if (ret)
+		dev_err(sev->dev, "SEV-SNP firmware DF_FLUSH failed\n");
+
+	sev->snp_inited = false;
+	sev->state = SEV_STATE_UNINIT;
+	dev_dbg(sev->dev, "SEV-SNP firmware shutdown\n");
+
+	return ret;
+}
+
+static int sev_snp_shutdown(int *error)
+{
+	int rc;
+
+	mutex_lock(&sev_cmd_mutex);
+	rc = __sev_snp_shutdown_locked(NULL);
+	mutex_unlock(&sev_cmd_mutex);
+
+	return rc;
+}
+
 static int sev_ioctl_do_pek_import(struct sev_issue_cmd *argp, bool writable)
 {
 	struct sev_device *sev = psp_master->sev_data;
@@ -1043,6 +1133,42 @@ int sev_issue_cmd_external_user(struct file *filep, unsigned int cmd,
 }
 EXPORT_SYMBOL_GPL(sev_issue_cmd_external_user);
 
+static int sev_snp_firmware_state(void)
+{
+	struct sev_data_snp_platform_status_buf *buf = NULL;
+	struct page *status_page = NULL;
+	int state = SEV_STATE_UNINIT;
+	int rc, error;
+
+	status_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+	if (!status_page)
+		return -ENOMEM;
+
+	buf = kzalloc(sizeof(*buf), GFP_KERNEL_ACCOUNT);
+	if (!buf) {
+		__free_page(status_page);
+		return -ENOMEM;
+	}
+
+	buf->status_paddr = __sme_page_pa(status_page);
+	rc = sev_do_cmd(SEV_CMD_SNP_PLATFORM_STATUS, buf, &error);
+
+	/*
+	 * The status buffer is allocated as a hypervisor page. As per the SEV spec,
+	 * if the firmware is in INIT state then status buffer must be either a
+	 * the firmware page or the default page. Since our status buffer is in
+	 * the hypervisor page, so, if firmware is in INIT state then we should
+	 * fail with INVALID_PAGE_STATE.
+	 */
+	if (rc && error == SEV_RET_INVALID_PAGE_STATE)
+		state = SEV_STATE_INIT;
+
+	kfree(buf);
+	__free_page(status_page);
+
+	return state;
+}
+
 void sev_pci_init(void)
 {
 	struct sev_device *sev = psp_master->sev_data;
@@ -1052,8 +1178,20 @@ void sev_pci_init(void)
 	if (!sev)
 		return;
 
+	/* Check if the SEV feature is enabled */
+	if (!boot_cpu_has(X86_FEATURE_SEV)) {
+		dev_err(sev->dev, "SEV: Memory Encryption is disabled by the BIOS\n");
+		return;
+	}
+
 	psp_timeout = psp_probe_timeout;
 
+	/* check if SNP firmware is in INIT state, If so shutdown */
+	if (boot_cpu_has(X86_FEATURE_SEV_SNP)) {
+		if (sev_snp_firmware_state() == SEV_STATE_INIT)
+			sev_snp_shutdown(NULL);
+	}
+
 	if (sev_get_api_version())
 		goto err;
 
@@ -1086,6 +1224,21 @@ void sev_pci_init(void)
 			 "SEV: TMR allocation failed, SEV-ES support unavailable\n");
 	}
 
+	/*
+	 * If boot CPU supports the SNP, then let first attempt to initialize
+	 * the SNP firmware.
+	 */
+	if (boot_cpu_has(X86_FEATURE_SEV_SNP)) {
+		rc = sev_snp_init(&error);
+		if (rc) {
+			/*
+			 * If we failed to INIT SNP then don't abort the probe.
+			 * Continue to initialize the legacy SEV firmware.
+			 */
+			dev_err(sev->dev, "SEV-SNP: failed to INIT error %#x\n", error);
+		}
+	}
+
 	/* Initialize the platform */
 	rc = sev_platform_init(&error);
 	if (rc && (error == SEV_RET_SECURE_DATA_INVALID)) {
@@ -1105,8 +1258,8 @@ void sev_pci_init(void)
 		return;
 	}
 
-	dev_info(sev->dev, "SEV API:%d.%d build:%d\n", sev->api_major,
-		 sev->api_minor, sev->build);
+	dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_inited ?
+		"-SNP" : "", sev->api_major, sev->api_minor, sev->build);
 
 	return;
 
@@ -1119,7 +1272,12 @@ void sev_pci_exit(void)
 	if (!psp_master->sev_data)
 		return;
 
-	sev_platform_shutdown(NULL);
+	if (boot_cpu_has(X86_FEATURE_SEV))
+		sev_platform_shutdown(NULL);
+
+	if (boot_cpu_has(X86_FEATURE_SEV_SNP))
+		sev_snp_shutdown(NULL);
+
 
 	if (sev_es_tmr) {
 		/* The TMR area was encrypted, flush it from the cache */
diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
index dd5c4fe82914..18b116a817ff 100644
--- a/drivers/crypto/ccp/sev-dev.h
+++ b/drivers/crypto/ccp/sev-dev.h
@@ -52,6 +52,8 @@ struct sev_device {
 	u8 api_major;
 	u8 api_minor;
 	u8 build;
+
+	bool snp_inited;
 };
 
 int sev_dev_init(struct psp_device *psp);
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index df89f0207099..ec45c18c3b0a 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -709,6 +709,20 @@ struct sev_data_snp_guest_request {
  */
 int sev_platform_init(int *error);
 
+/**
+ * sev_snp_init - perform SEV SNP_INIT command
+ *
+ * @error: SEV command return code
+ *
+ * Returns:
+ * 0 if the SEV successfully processed the command
+ * -%ENODEV    if the SEV device is not available
+ * -%ENOTSUPP  if the SEV does not support SEV
+ * -%ETIMEDOUT if the SEV command timed out
+ * -%EIO       if the SEV returned a non-zero return code
+ */
+int sev_snp_init(int *error);
+
 /**
  * sev_platform_status - perform SEV PLATFORM_STATUS command
  *
@@ -816,6 +830,8 @@ sev_platform_status(struct sev_user_data_status *status, int *error) { return -E
 
 static inline int sev_platform_init(int *error) { return -ENODEV; }
 
+static inline int sev_snp_init(int *error) { return -ENODEV; }
+
 static inline int
 sev_guest_deactivate(struct sev_data_deactivate *data, int *error) { return -ENODEV; }
 
-- 
2.17.1