[PATCH RFC v9 20/51] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled

[Michael Roth <michael.roth@amd.com>]

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>
[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 | 150 ++++++++++++++++++++++++++++++++---
 include/linux/psp-sev.h      |   9 +++
 2 files changed, 150 insertions(+), 9 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 88c5bf264a87..d8124d33c831 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -91,6 +91,13 @@ static void *sev_init_ex_buffer;
 struct sev_data_range_list *snp_range_list;
 static int __sev_snp_init_locked(int *error);
 
+/* 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;
@@ -191,11 +198,131 @@ static int sev_cmd_buffer_len(int cmd)
 	return 0;
 }
 
+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;
+
+	for (i = 0; i < npages; i++, pfn++, n++) {
+		struct sev_data_snp_page_reclaim data = {0};
+
+		data.paddr = pfn << PAGE_SHIFT;
+
+		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(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_leak_pages(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;
 
@@ -443,7 +570,7 @@ 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);
@@ -466,7 +593,7 @@ 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);
@@ -499,14 +626,16 @@ 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) {
 		init_function = __sev_init_ex_locked;
@@ -1001,6 +1130,8 @@ 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;
 }
 
@@ -1507,8 +1638,9 @@ 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 c8656a36baeb..5ae61de96e44 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -906,6 +906,8 @@ 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 */
 
@@ -933,6 +935,13 @@ 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