The behavior of the SEV-legacy commands is altered when the SNP firmware
is in the INIT state. When SNP is in INIT state, all the SEV-legacy
commands that cause the firmware to write to memory must be in the
firmware state before issuing the command..
See SEV-SNP spec section 5.3.7 for more detail.
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 | 90 +++++++++++++++++++++++++++++++++---
drivers/crypto/ccp/sev-dev.h | 1 +
2 files changed, 85 insertions(+), 6 deletions(-)
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 242c4775eb56..4aa9d4505d71 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -148,12 +148,35 @@ static int sev_cmd_buffer_len(int cmd)
return 0;
}
+static bool sev_legacy_cmd_buf_writable(int cmd)
+{
+ switch (cmd) {
+ case SEV_CMD_PLATFORM_STATUS:
+ case SEV_CMD_GUEST_STATUS:
+ case SEV_CMD_LAUNCH_START:
+ case SEV_CMD_RECEIVE_START:
+ case SEV_CMD_LAUNCH_MEASURE:
+ case SEV_CMD_SEND_START:
+ case SEV_CMD_SEND_UPDATE_DATA:
+ case SEV_CMD_SEND_UPDATE_VMSA:
+ case SEV_CMD_PEK_CSR:
+ case SEV_CMD_PDH_CERT_EXPORT:
+ case SEV_CMD_GET_ID:
+ return true;
+ default:
+ return false;
+ }
+}
+
static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
{
+ size_t cmd_buf_len = sev_cmd_buffer_len(cmd);
struct psp_device *psp = psp_master;
struct sev_device *sev;
unsigned int phys_lsb, phys_msb;
unsigned int reg, ret = 0;
+ struct page *cmd_page = NULL;
+ struct rmpupdate e = {};
if (!psp || !psp->sev_data)
return -ENODEV;
@@ -163,15 +186,47 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
sev = psp->sev_data;
+ /*
+ * Check If SNP is initialized and we are asked to execute a legacy
+ * command that requires write by the firmware in the command buffer.
+ * In that case use an intermediate command buffer page to complete the
+ * operation.
+ *
+ * NOTE: If the command buffer contains a pointer which will be modified
+ * by the firmware then caller must take care of it.
+ */
+ if (sev->snp_inited && sev_legacy_cmd_buf_writable(cmd)) {
+ cmd_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+ if (!cmd_page)
+ return -ENOMEM;
+
+ memcpy(page_address(cmd_page), data, cmd_buf_len);
+
+ /* make it as a firmware page */
+ e.immutable = true;
+ e.assigned = true;
+ ret = rmptable_rmpupdate(cmd_page, &e);
+ if (ret) {
+ dev_err(sev->dev, "sev cmd id %#x, failed to change to firmware state (spa 0x%lx ret %d).\n",
+ cmd, page_to_pfn(cmd_page) << PAGE_SHIFT, ret);
+ goto e_free;
+ }
+ }
+
/* Get the physical address of the command buffer */
- phys_lsb = data ? lower_32_bits(__psp_pa(data)) : 0;
- phys_msb = data ? upper_32_bits(__psp_pa(data)) : 0;
+ if (cmd_page) {
+ phys_lsb = data ? lower_32_bits(__sme_page_pa(cmd_page)) : 0;
+ phys_msb = data ? upper_32_bits(__sme_page_pa(cmd_page)) : 0;
+ } else {
+ phys_lsb = data ? lower_32_bits(__psp_pa(data)) : 0;
+ phys_msb = data ? upper_32_bits(__psp_pa(data)) : 0;
+ }
dev_dbg(sev->dev, "sev command id %#x buffer 0x%08x%08x timeout %us\n",
cmd, phys_msb, phys_lsb, psp_timeout);
print_hex_dump_debug("(in): ", DUMP_PREFIX_OFFSET, 16, 2, data,
- sev_cmd_buffer_len(cmd), false);
+ cmd_buf_len, false);
iowrite32(phys_lsb, sev->io_regs + sev->vdata->cmdbuff_addr_lo_reg);
iowrite32(phys_msb, sev->io_regs + sev->vdata->cmdbuff_addr_hi_reg);
@@ -185,6 +240,24 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
/* wait for command completion */
ret = sev_wait_cmd_ioc(sev, ®, psp_timeout);
+
+ /* if an intermediate page is used then copy the data back to original. */
+ if (cmd_page) {
+ int rc;
+
+ /* make it as a hypervisor page */
+ memset(&e, 0, sizeof(struct rmpupdate));
+ rc = rmptable_rmpupdate(cmd_page, &e);
+ if (rc) {
+ dev_err(sev->dev, "sev cmd id %#x, failed to change to hypervisor state ret=%d.\n",
+ cmd, rc);
+ /* Set the command page to NULL so that the page is leaked. */
+ cmd_page = NULL;
+ } else {
+ memcpy(data, page_address(cmd_page), cmd_buf_len);
+ }
+ }
+
if (ret) {
if (psp_ret)
*psp_ret = 0;
@@ -192,7 +265,7 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
dev_err(sev->dev, "sev command %#x timed out, disabling PSP\n", cmd);
psp_dead = true;
- return ret;
+ goto e_free;
}
psp_timeout = psp_cmd_timeout;
@@ -207,8 +280,11 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
}
print_hex_dump_debug("(out): ", DUMP_PREFIX_OFFSET, 16, 2, data,
- sev_cmd_buffer_len(cmd), false);
+ cmd_buf_len, false);
+e_free:
+ if (cmd_page)
+ __free_page(cmd_page);
return ret;
}
@@ -234,7 +310,7 @@ static int __sev_platform_init_locked(int *error)
sev = psp->sev_data;
- if (sev->state == SEV_STATE_INIT)
+ if (sev->legacy_inited && (sev->state == SEV_STATE_INIT))
return 0;
if (sev_es_tmr) {
@@ -255,6 +331,7 @@ static int __sev_platform_init_locked(int *error)
if (rc)
return rc;
+ sev->legacy_inited = true;
sev->state = SEV_STATE_INIT;
/* Prepare for first SEV guest launch after INIT */
@@ -289,6 +366,7 @@ static int __sev_platform_shutdown_locked(int *error)
if (ret)
return ret;
+ sev->legacy_inited = false;
sev->state = SEV_STATE_UNINIT;
dev_dbg(sev->dev, "SEV firmware shutdown\n");
diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
index 18b116a817ff..2ee9665a901d 100644
--- a/drivers/crypto/ccp/sev-dev.h
+++ b/drivers/crypto/ccp/sev-dev.h
@@ -54,6 +54,7 @@ struct sev_device {
u8 build;
bool snp_inited;
+ bool legacy_inited;
};
int sev_dev_init(struct psp_device *psp);
--
2.17.1
