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crypto: ccp - Fix locking on alloc failure handling

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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 24512afa43 ("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: 24512afa43 ("crypto: ccp: Handle the legacy TMR allocation when SNP is enabled")
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Pratik R. Sampat <prsampat@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Alexey Kardashevskiy
2025-06-17 19:43:54 +10:00
committed by Herbert Xu
parent a71d3e1beb
commit b4abeccb8d
1 changed files with 4 additions and 4 deletions
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8
drivers/crypto/ccp/sev-dev.c
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@@ -434,7 +434,7 @@ cleanup:
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;
@@ -453,7 +453,7 @@ 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;
@@ -463,7 +463,7 @@ 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;
}
@@ -498,7 +498,7 @@ 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;