crypto: ccp - Fix locking on alloc failure handling

JIRA: https://issues.redhat.com/browse/RHEL-106909
JIRA: https://issues.redhat.com/browse/RHEL-107608
Upstream Status: merged into the linux.git

commit b4abecc
Author: Alexey Kardashevskiy <[email protected]>
Date:   Tue Jun 17 19:43:54 2025 +1000

    crypto: ccp - Fix locking on alloc failure handling

    The __snp_alloc_firmware_pages() helper allocates pages in the firmware
    state (alloc + rmpupdate). In case of failed rmpupdate, it tries
    reclaiming pages with already changed state. This requires calling
    the PSP firmware and since there is sev_cmd_mutex to guard such calls,
    the helper takes a "locked" parameter so specify if the lock needs to
    be held.

    Most calls happen from snp_alloc_firmware_page() which executes without
    the lock. However

    commit 24512af ("crypto: ccp: Handle the legacy TMR allocation when SNP is enabled")

    switched sev_fw_alloc() from alloc_pages() (which does not call the PSP) to
    __snp_alloc_firmware_pages() (which does) but did not account for the fact
    that sev_fw_alloc() is called from __sev_platform_init_locked()
    (via __sev_platform_init_handle_tmr()) and executes with the lock held.

    Add a "locked" parameter to __snp_alloc_firmware_pages().
    Make sev_fw_alloc() use the new parameter to prevent potential deadlock in
    rmp_mark_pages_firmware() if rmpupdate() failed.

    Fixes: 24512af ("crypto: ccp: Handle the legacy TMR allocation when SNP is enabled")
    Signed-off-by: Alexey Kardashevskiy <[email protected]>
    Reviewed-by: Tom Lendacky <[email protected]>
    Reviewed-by: Pratik R. Sampat <[email protected]>
    Signed-off-by: Herbert Xu <[email protected]>

Signed-off-by: Vladis Dronov <[email protected]>

Author: nefigtut

drivers/crypto/ccp/sev-dev.c

@@ -433,7 +433,7 @@ static int rmp_mark_pages_firmware(unsigned long paddr, unsigned int npages, boo
 	return rc;
 }
 
-static struct page *__snp_alloc_firmware_pages(gfp_t gfp_mask, int order)
+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;
@@ -452,7 +452,7 @@ static struct page *__snp_alloc_firmware_pages(gfp_t gfp_mask, int order)
 		return page;
 
 	paddr = __pa((unsigned long)page_address(page));
-	if (rmp_mark_pages_firmware(paddr, npages, false))
+	if (rmp_mark_pages_firmware(paddr, npages, locked))
 		return NULL;
 
 	return page;
@@ -462,7 +462,7 @@ void *snp_alloc_firmware_page(gfp_t gfp_mask)
 {
 	struct page *page;
 
-	page = __snp_alloc_firmware_pages(gfp_mask, 0);
+	page = __snp_alloc_firmware_pages(gfp_mask, 0, false);
 
 	return page ? page_address(page) : NULL;
 }
@@ -497,7 +497,7 @@ static void *sev_fw_alloc(unsigned long len)
 {
 	struct page *page;
 
-	page = __snp_alloc_firmware_pages(GFP_KERNEL, get_order(len));
+	page = __snp_alloc_firmware_pages(GFP_KERNEL, get_order(len), true);
 	if (!page)
 		return NULL;