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From:   Michael Roth <michael.roth@amd.com>
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Subject: [PATCH RFC v7 28/64] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled
Date:   Wed, 14 Dec 2022 13:40:20 -0600
Message-ID: <20221214194056.161492-29-michael.roth@amd.com>
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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