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Subject[RFC Part2 PATCH 09/30] crypto: ccp: Add support to initialize the AMD-SP for SEV-SNP
Date
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@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
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
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