[PATCH v1 16/26] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled

Michael Roth
2023-12-30T16:24:19Z

From: Brijesh Singh <brijesh.singh@amd.com>

The behavior and requirement for the SEV-legacy command is altered when
the SNP firmware is in the INIT state. See SEV-SNP firmware specification
for more details.

Allocate the Trusted Memory Region (TMR) as a 2mb sized/aligned region
when SNP is enabled to satisfy new requirements for SNP. Continue
allocating a 1mb region for !SNP configuration.

While at it, provide an API to allocate a firmware page. The KVM driver
needs to allocate a firmware context page during the guest creation. The
context page needs to be updated by the firmware. See the SEV-SNP
specification for further details.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Co-developed-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
[mdr: use struct sev_data_snp_page_reclaim instead of passing paddr
directly to SEV_CMD_SNP_PAGE_RECLAIM]
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
drivers/crypto/ccp/sev-dev.c | 176 +++++++++++++++++++++++++++++++----
include/linux/psp-sev.h | 9 ++
2 files changed, 165 insertions(+), 20 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 767f0ec3d5bb..307eb3e7c354 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -30,6 +30,7 @@
#include <asm/smp.h>
#include <asm/cacheflush.h>
#include <asm/e820/types.h>
+#include <asm/sev.h>

#include "psp-dev.h"
#include "sev-dev.h"
@@ -73,9 +74,14 @@ static int psp_timeout;
* The TMR is a 1MB area that must be 1MB aligned. Use the page allocator
* to allocate the memory, which will return aligned memory for the specified
* allocation order.
+ *
+ * When SEV-SNP is enabled the TMR needs to be 2MB aligned and 2MB sized.
*/
-#define SEV_ES_TMR_SIZE (1024 * 1024)
+#define SEV_TMR_SIZE (1024 * 1024)
+#define SNP_TMR_SIZE (2 * 1024 * 1024)
+
static void *sev_es_tmr;
+static size_t sev_es_tmr_size = SEV_TMR_SIZE;

/* INIT_EX NV Storage:
* The NV Storage is a 32Kb area and must be 4Kb page aligned. Use the page
@@ -192,17 +198,6 @@ static int sev_cmd_buffer_len(int cmd)
return 0;
}

-static void *sev_fw_alloc(unsigned long len)
-{
- struct page *page;
-
- page = alloc_pages(GFP_KERNEL, get_order(len));
- if (!page)
- return NULL;
-
- return page_address(page);
-}
-
static struct file *open_file_as_root(const char *filename, int flags, umode_t mode)
{
struct file *fp;
@@ -333,6 +328,142 @@ static int sev_write_init_ex_file_if_required(int cmd_id)
return sev_write_init_ex_file();
}

+/*
+ * snp_reclaim_pages() needs __sev_do_cmd_locked(), and __sev_do_cmd_locked()
+ * needs snp_reclaim_pages(), so a forward declaration is needed.
+ */
+static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret);
+
+static int snp_reclaim_pages(unsigned long paddr, unsigned int npages, bool locked)
+{
+ int ret, err, i;
+
+ paddr = __sme_clr(paddr);
+
+ for (i = 0; i < npages; i++, paddr += PAGE_SIZE) {
+ struct sev_data_snp_page_reclaim data = {0};
+
+ data.paddr = paddr;
+
+ if (locked)
+ ret = __sev_do_cmd_locked(SEV_CMD_SNP_PAGE_RECLAIM, &data, &err);
+ else
+ ret = sev_do_cmd(SEV_CMD_SNP_PAGE_RECLAIM, &data, &err);
+
+ if (ret)
+ goto cleanup;
+
+ ret = rmp_make_shared(__phys_to_pfn(paddr), PG_LEVEL_4K);
+ if (ret)
+ goto cleanup;
+ }
+
+ return 0;
+
+cleanup:
+ /*
+ * If there was a failure reclaiming the page then it is no longer safe
+ * to release it back to the system; leak it instead.
+ */
+ snp_leak_pages(__phys_to_pfn(paddr), npages - i);
+ return ret;
+}
+
+static int rmp_mark_pages_firmware(unsigned long paddr, unsigned int npages, bool locked)
+{
+ unsigned long pfn = __sme_clr(paddr) >> PAGE_SHIFT;
+ int rc, i;
+
+ for (i = 0; i < npages; i++, pfn++) {
+ rc = rmp_make_private(pfn, 0, PG_LEVEL_4K, 0, true);
+ if (rc)
+ goto cleanup;
+ }
+
+ return 0;
+
+cleanup:
+ /*
+ * Try unrolling the firmware state changes by
+ * reclaiming the pages which were already changed to the
+ * firmware state.
+ */
+ snp_reclaim_pages(paddr, i, locked);
+
+ return rc;
+}
+
+static struct page *__snp_alloc_firmware_pages(gfp_t gfp_mask, int order)
+{
+ unsigned long npages = 1ul << order, paddr;
+ struct sev_device *sev;
+ struct page *page;
+
+ if (!psp_master || !psp_master->sev_data)
+ return NULL;
+
+ page = alloc_pages(gfp_mask, order);
+ if (!page)
+ return NULL;
+
+ /* If SEV-SNP is initialized then add the page in RMP table. */
+ sev = psp_master->sev_data;
+ if (!sev->snp_initialized)
+ return page;
+
+ paddr = __pa((unsigned long)page_address(page));
+ if (rmp_mark_pages_firmware(paddr, npages, false))
+ return NULL;
+
+ return page;
+}
+
+void *snp_alloc_firmware_page(gfp_t gfp_mask)
+{
+ struct page *page;
+
+ page = __snp_alloc_firmware_pages(gfp_mask, 0);
+
+ return page ? page_address(page) : NULL;
+}
+EXPORT_SYMBOL_GPL(snp_alloc_firmware_page);
+
+static void __snp_free_firmware_pages(struct page *page, int order, bool locked)
+{
+ struct sev_device *sev = psp_master->sev_data;
+ unsigned long paddr, npages = 1ul << order;
+
+ if (!page)
+ return;
+
+ paddr = __pa((unsigned long)page_address(page));
+ if (sev->snp_initialized &&
+ snp_reclaim_pages(paddr, npages, locked))
+ return;
+
+ __free_pages(page, order);
+}
+
+void snp_free_firmware_page(void *addr)
+{
+ if (!addr)
+ return;
+
+ __snp_free_firmware_pages(virt_to_page(addr), 0, false);
+}
+EXPORT_SYMBOL_GPL(snp_free_firmware_page);
+
+static void *sev_fw_alloc(unsigned long len)
+{
+ struct page *page;
+
+ page = __snp_alloc_firmware_pages(GFP_KERNEL, get_order(len));
+ if (!page)
+ return NULL;
+
+ return page_address(page);
+}
+
static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
{
struct psp_device *psp = psp_master;
@@ -456,7 +587,7 @@ static int __sev_init_locked(int *error)
data.tmr_address = __pa(sev_es_tmr);

data.flags |= SEV_INIT_FLAGS_SEV_ES;
- data.tmr_len = SEV_ES_TMR_SIZE;
+ data.tmr_len = sev_es_tmr_size;
}

return __sev_do_cmd_locked(SEV_CMD_INIT, &data, error);
@@ -479,7 +610,7 @@ static int __sev_init_ex_locked(int *error)
data.tmr_address = __pa(sev_es_tmr);

data.flags |= SEV_INIT_FLAGS_SEV_ES;
- data.tmr_len = SEV_ES_TMR_SIZE;
+ data.tmr_len = sev_es_tmr_size;
}

return __sev_do_cmd_locked(SEV_CMD_INIT_EX, &data, error);
@@ -625,6 +756,8 @@ static int __sev_snp_init_locked(int *error)
sev->snp_initialized = true;
dev_dbg(sev->dev, "SEV-SNP firmware initialized\n");

+ sev_es_tmr_size = SNP_TMR_SIZE;
+
return rc;
}

@@ -643,14 +776,16 @@ static int __sev_platform_init_locked(int *error)

if (!sev_es_tmr) {
/* Obtain the TMR memory area for SEV-ES use */
- sev_es_tmr = sev_fw_alloc(SEV_ES_TMR_SIZE);
- if (sev_es_tmr)
+ sev_es_tmr = sev_fw_alloc(sev_es_tmr_size);
+ if (sev_es_tmr) {
/* Must flush the cache before giving it to the firmware */
- clflush_cache_range(sev_es_tmr, SEV_ES_TMR_SIZE);
- else
+ if (!sev->snp_initialized)
+ clflush_cache_range(sev_es_tmr, sev_es_tmr_size);
+ } else {
dev_warn(sev->dev,
"SEV: TMR allocation failed, SEV-ES support unavailable\n");
}
+ }

if (sev_init_ex_buffer) {
rc = sev_read_init_ex_file();
@@ -1548,8 +1683,9 @@ static void sev_firmware_shutdown(struct sev_device *sev)
/* The TMR area was encrypted, flush it from the cache */
wbinvd_on_all_cpus();

- free_pages((unsigned long)sev_es_tmr,
- get_order(SEV_ES_TMR_SIZE));
+ __snp_free_firmware_pages(virt_to_page(sev_es_tmr),
+ get_order(sev_es_tmr_size),
+ false);
sev_es_tmr = NULL;
}

diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index 0581f194cdd0..16d0da895680 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -931,6 +931,8 @@ int sev_guest_decommission(struct sev_data_decommission *data, int *error);
int sev_do_cmd(int cmd, void *data, int *psp_ret);

void *psp_copy_user_blob(u64 uaddr, u32 len);
+void *snp_alloc_firmware_page(gfp_t mask);
+void snp_free_firmware_page(void *addr);

#else /* !CONFIG_CRYPTO_DEV_SP_PSP */

@@ -958,6 +960,13 @@ sev_issue_cmd_external_user(struct file *filep, unsigned int id, void *data, int

static inline void *psp_copy_user_blob(u64 __user uaddr, u32 len) { return ERR_PTR(-EINVAL); }

+static inline void *snp_alloc_firmware_page(gfp_t mask)
+{
+ return NULL;
+}
+
+static inline void snp_free_firmware_page(void *addr) { }
+
#endif /* CONFIG_CRYPTO_DEV_SP_PSP */

#endif /* __PSP_SEV_H__ */
--
2.25.1