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Subject[PATCH RFC v7 28/64] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled
Date
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 the SNP. Continue
allocating a 1mb region for !SNP configuration.

While at it, provide API that can be used by others to allocate a page
that can be used by the firmware. The immediate user for this API will
be the KVM driver. The KVM driver to need to allocate a firmware context
page during the guest creation. The context page need to be updated
by the firmware. See the SEV-SNP specification for further details.

Co-developed-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
drivers/crypto/ccp/sev-dev.c | 148 +++++++++++++++++++++++++++++++++--
include/linux/psp-sev.h | 9 +++
2 files changed, 149 insertions(+), 8 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index eca4e59b0f44..4c12e98a1219 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -94,6 +94,13 @@ static void *sev_init_ex_buffer;
*/
struct sev_data_range_list *snp_range_list;

+/* When SEV-SNP is enabled the TMR needs to be 2MB aligned and 2MB size. */
+#define SEV_SNP_ES_TMR_SIZE (2 * 1024 * 1024)
+
+static size_t sev_es_tmr_size = SEV_ES_TMR_SIZE;
+
+static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret);
+
static inline bool sev_version_greater_or_equal(u8 maj, u8 min)
{
struct sev_device *sev = psp_master->sev_data;
@@ -216,11 +223,134 @@ void snp_mark_pages_offline(unsigned long pfn, unsigned int npages)
}
EXPORT_SYMBOL_GPL(snp_mark_pages_offline);

+static int snp_reclaim_pages(unsigned long paddr, unsigned int npages, bool locked)
+{
+ /* Cbit maybe set in the paddr */
+ unsigned long pfn = __sme_clr(paddr) >> PAGE_SHIFT;
+ int ret, err, i, n = 0;
+
+ if (!pfn_valid(pfn)) {
+ pr_err("%s: Invalid PFN %lx\n", __func__, pfn);
+ return 0;
+ }
+
+ for (i = 0; i < npages; i++, pfn++, n++) {
+ paddr = pfn << PAGE_SHIFT;
+
+ if (locked)
+ ret = __sev_do_cmd_locked(SEV_CMD_SNP_PAGE_RECLAIM, &paddr, &err);
+ else
+ ret = sev_do_cmd(SEV_CMD_SNP_PAGE_RECLAIM, &paddr, &err);
+
+ if (ret)
+ goto cleanup;
+
+ ret = rmp_make_shared(pfn, PG_LEVEL_4K);
+ if (ret)
+ goto cleanup;
+ }
+
+ return 0;
+
+cleanup:
+ /*
+ * If failed to reclaim the page then page is no longer safe to
+ * be release back to the system, leak it.
+ */
+ snp_mark_pages_offline(pfn, npages - n);
+ return ret;
+}
+
+static int rmp_mark_pages_firmware(unsigned long paddr, unsigned int npages, bool locked)
+{
+ /* Cbit maybe set in the paddr */
+ unsigned long pfn = __sme_clr(paddr) >> PAGE_SHIFT;
+ int rc, n = 0, i;
+
+ for (i = 0; i < npages; i++, n++, 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, n, locked);
+
+ return rc;
+}
+
+static struct page *__snp_alloc_firmware_pages(gfp_t gfp_mask, int order, bool locked)
+{
+ 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, locked))
+ return NULL;
+
+ return page;
+}
+
+void *snp_alloc_firmware_page(gfp_t gfp_mask)
+{
+ struct page *page;
+
+ page = __snp_alloc_firmware_pages(gfp_mask, 0, false);
+
+ 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 = alloc_pages(GFP_KERNEL, get_order(len));
+ page = __snp_alloc_firmware_pages(GFP_KERNEL, get_order(len), false);
if (!page)
return NULL;

@@ -468,7 +598,7 @@ 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);
@@ -491,7 +621,7 @@ 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);
@@ -982,6 +1112,8 @@ 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 = SEV_SNP_ES_TMR_SIZE;
+
return rc;
}

@@ -1499,8 +1631,9 @@ 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;
}

@@ -1511,8 +1644,7 @@ static void sev_firmware_shutdown(struct sev_device *sev)
}

if (snp_range_list) {
- free_pages((unsigned long)snp_range_list,
- get_order(PAGE_SIZE));
+ snp_free_firmware_page(snp_range_list);
snp_range_list = NULL;
}

@@ -1593,7 +1725,7 @@ void sev_pci_init(void)
}

/* Obtain the TMR memory area for SEV-ES use */
- sev_es_tmr = sev_fw_alloc(SEV_ES_TMR_SIZE);
+ sev_es_tmr = sev_fw_alloc(sev_es_tmr_size);
if (!sev_es_tmr)
dev_warn(sev->dev,
"SEV: TMR allocation failed, SEV-ES support unavailable\n");
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index 8edf5c548fbf..d19744807471 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -922,6 +922,8 @@ 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);

/**
* sev_mark_pages_offline - insert non-reclaimed firmware/guest pages
@@ -959,6 +961,13 @@ static inline void *psp_copy_user_blob(u64 __user uaddr, u32 len) { return ERR_P

void snp_mark_pages_offline(unsigned long pfn, unsigned int npages) {}

+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
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