The function can be used to get the current SEV capabilities.
The capabilities include platform diffie-hellman key (pdh) and certificate
chain. The key can be provided to the external entities which wants to
establish a trusted channel between SEV firmware and guest owner.
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Cc: Eduardo Habkost <ehabkost@xxxxxxxxxx>
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
target/i386/monitor.c | 11 +++++--
target/i386/sev-stub.c | 5 +++
target/i386/sev.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++
target/i386/sev_i386.h | 1 +
4 files changed, 98 insertions(+), 2 deletions(-)
diff --git a/target/i386/monitor.c b/target/i386/monitor.c
index 33e6bade693b..79fa9bd7a3e3 100644
--- a/target/i386/monitor.c
+++ b/target/i386/monitor.c
@@ -740,6 +740,13 @@ SevLaunchMeasureInfo *qmp_query_sev_launch_measure(Error **errp)
SevCapability *qmp_query_sev_capabilities(Error **errp)
{
- error_setg(errp, "SEV feature is not available");
- return NULL;
+ SevCapability *data;
+
+ data = sev_get_capabilities();
+ if (!data) {
+ error_setg(errp, "SEV feature is not available");
+ return NULL;
+ }
+
+ return data;
}
diff --git a/target/i386/sev-stub.c b/target/i386/sev-stub.c
index 2f61c32ec975..59a003a4ebe6 100644
--- a/target/i386/sev-stub.c
+++ b/target/i386/sev-stub.c
@@ -44,3 +44,8 @@ char *sev_get_launch_measurement(void)
{
return NULL;
}
+
+SevCapability *sev_get_capabilities(void)
+{
+ return NULL;
+}
diff --git a/target/i386/sev.c b/target/i386/sev.c
index b9bfce95246a..1d0cb8435e0f 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -427,6 +427,89 @@ sev_get_info(void)
return info;
}
+static int
+sev_get_pdh_info(int fd, guchar **pdh, size_t *pdh_len, guchar **cert_chain,
+ size_t *cert_chain_len)
+{
+ guchar *pdh_data, *cert_chain_data;
+ struct sev_user_data_pdh_cert_export export = {};
+ int err, r;
+
+ /* query the certificate length */
+ r = sev_platform_ioctl(fd, SEV_PDH_CERT_EXPORT, &export, &err);
+ if (r < 0) {
+ if (err != SEV_RET_INVALID_LEN) {
+ error_report("failed to export PDH cert ret=%d fw_err=%d (%s)",
+ r, err, fw_error_to_str(err));
+ return 1;
+ }
+ }
+
+ pdh_data = g_new(guchar, export.pdh_cert_len);
+ cert_chain_data = g_new(guchar, export.cert_chain_len);
+ export.pdh_cert_address = (unsigned long)pdh_data;
+ export.cert_chain_address = (unsigned long)cert_chain_data;
+
+ r = sev_platform_ioctl(fd, SEV_PDH_CERT_EXPORT, &export, &err);
+ if (r < 0) {
+ error_report("failed to export PDH cert ret=%d fw_err=%d (%s)",
+ r, err, fw_error_to_str(err));
+ goto e_free;
+ }
+
+ *pdh = pdh_data;
+ *pdh_len = export.pdh_cert_len;
+ *cert_chain = cert_chain_data;
+ *cert_chain_len = export.cert_chain_len;
+ return 0;
+
+e_free:
+ g_free(pdh_data);
+ g_free(cert_chain_data);
+ return 1;
+}
+
+SevCapability *
+sev_get_capabilities(void)
+{
+ SevCapability *cap;
+ guchar *pdh_data, *cert_chain_data;
+ size_t pdh_len = 0, cert_chain_len = 0;
+ uint32_t ebx;
+ int fd;
+
+ fd = open(DEFAULT_SEV_DEVICE, O_RDWR);
+ if (fd < 0) {
+ error_report("%s: Failed to open %s '%s'", __func__,
+ DEFAULT_SEV_DEVICE, strerror(errno));
+ return NULL;
+ }
+
+ if (sev_get_pdh_info(fd, &pdh_data, &pdh_len,
+ &cert_chain_data, &cert_chain_len)) {
+ return NULL;
+ }
+
+ cap = g_new0(SevCapability, 1);
+ cap->pdh = g_base64_encode(pdh_data, pdh_len);
+ cap->cert_chain = g_base64_encode(cert_chain_data, cert_chain_len);
+
+ host_cpuid(0x8000001F, 0, NULL, &ebx, NULL, NULL);
+ cap->cbitpos = ebx & 0x3f;
+
+ /*
+ * When SEV feature is enabled, we loose one bit in guest physical
+ * addressing.
+ */
+ cap->reduced_phys_bits = 1;
+
+ g_free(pdh_data);
+ g_free(cert_chain_data);
+
+ close(fd);
+ return cap;
+}
+
static int
sev_read_file_base64(const char *filename, guchar **data, gsize *len)
{
diff --git a/target/i386/sev_i386.h b/target/i386/sev_i386.h
index 6e370775770e..b8622dfb1e49 100644
--- a/target/i386/sev_i386.h
+++ b/target/i386/sev_i386.h
@@ -38,6 +38,7 @@ extern SevInfo *sev_get_info(void);
extern uint32_t sev_get_cbit_position(void);
extern uint32_t sev_get_reduced_phys_bits(void);
extern char *sev_get_launch_measurement(void);
+extern SevCapability *sev_get_capabilities(void);
typedef struct QSevGuestInfo QSevGuestInfo;
typedef struct QSevGuestInfoClass QSevGuestInfoClass;
--
2.14.3
