linux-kernel - [PATCH kernel v2 1/5] ccp: Make snp_reclaim_pages and __sev_do_cmd

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Message-ID: <20251121080629.444992-2-aik@amd.com>
Date: Fri, 21 Nov 2025 19:06:25 +1100
From: Alexey Kardashevskiy <aik@....com>
To: <linux-kernel@...r.kernel.org>
CC: <linux-crypto@...r.kernel.org>, Tom Lendacky <thomas.lendacky@....com>,
	John Allen <john.allen@....com>, Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>, Ashish Kalra <ashish.kalra@....com>,
	Joerg Roedel <joro@...tes.org>, Suravee Suthikulpanit
	<suravee.suthikulpanit@....com>, Will Deacon <will@...nel.org>, Robin Murphy
	<robin.murphy@....com>, "Borislav Petkov (AMD)" <bp@...en8.de>, Kim Phillips
	<kim.phillips@....com>, Jerry Snitselaar <jsnitsel@...hat.com>, Vasant Hegde
	<vasant.hegde@....com>, Jason Gunthorpe <jgg@...pe.ca>, Gao Shiyuan
	<gaoshiyuan@...du.com>, Sean Christopherson <seanjc@...gle.com>, "Nikunj A
 Dadhania" <nikunj@....com>, Michael Roth <michael.roth@....com>, Amit Shah
	<amit.shah@....com>, Peter Gonda <pgonda@...gle.com>,
	<iommu@...ts.linux.dev>, Alexey Kardashevskiy <aik@....com>
Subject: [PATCH kernel v2 1/5] ccp: Make snp_reclaim_pages and __sev_do_cmd_locked public

The snp_reclaim_pages() helper reclaims pages in the FW state. SEV-TIO
and the TMPM driver (a hardware engine which smashes IOMMU PDEs among
other things) will use to reclaim memory when cleaning up.

Share and export snp_reclaim_pages().

Most of the SEV-TIO code uses sev_do_cmd() which locks the sev_cmd_mutex
and already exported. But the SNP init code (which also sets up SEV-TIO)
executes under the sev_cmd_mutex lock so the SEV-TIO code has to use
the __sev_do_cmd_locked() helper. This one though does not need to be
exported/shared globally as SEV-TIO is a part of the CCP driver still.

Share __sev_do_cmd_locked() via the CCP internal header.

Signed-off-by: Alexey Kardashevskiy <aik@....com>
---
 drivers/crypto/ccp/sev-dev.h |  2 ++
 include/linux/psp-sev.h      |  6 ++++++
 drivers/crypto/ccp/sev-dev.c | 11 +++--------
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
index ac03bd0848f7..b9029506383f 100644
--- a/drivers/crypto/ccp/sev-dev.h
+++ b/drivers/crypto/ccp/sev-dev.h
@@ -66,6 +66,8 @@ struct sev_device {
 int sev_dev_init(struct psp_device *psp);
 void sev_dev_destroy(struct psp_device *psp);
 
+int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret);
+
 void sev_pci_init(void);
 void sev_pci_exit(void);
 
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index e0dbcb4b4fd9..34a25209f909 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -992,6 +992,7 @@ 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);
+int snp_reclaim_pages(unsigned long paddr, unsigned int npages, bool locked);
 void snp_free_firmware_page(void *addr);
 void sev_platform_shutdown(void);
 bool sev_is_snp_ciphertext_hiding_supported(void);
@@ -1027,6 +1028,11 @@ static inline void *snp_alloc_firmware_page(gfp_t mask)
 	return NULL;
 }
 
+static inline int snp_reclaim_pages(unsigned long paddr, unsigned int npages, bool locked)
+{
+	return -ENODEV;
+}
+
 static inline void snp_free_firmware_page(void *addr) { }
 
 static inline void sev_platform_shutdown(void) { }
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 0d13d47c164b..9e0c16b36f9c 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -387,13 +387,7 @@ static int sev_write_init_ex_file_if_required(int cmd_id)
 	return sev_write_init_ex_file();
 }
 
-/*
- * snp_reclaim_pages() needs __sev_do_cmd_locked(), and __sev_do_cmd_locked()
- * needs snp_reclaim_pages(), so a forward declaration is needed.
- */
-static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret);
-
-static int snp_reclaim_pages(unsigned long paddr, unsigned int npages, bool locked)
+int snp_reclaim_pages(unsigned long paddr, unsigned int npages, bool locked)
 {
 	int ret, err, i;
 
@@ -427,6 +421,7 @@ static int snp_reclaim_pages(unsigned long paddr, unsigned int npages, bool lock
 	snp_leak_pages(__phys_to_pfn(paddr), npages - i);
 	return ret;
 }
+EXPORT_SYMBOL_GPL(snp_reclaim_pages);
 
 static int rmp_mark_pages_firmware(unsigned long paddr, unsigned int npages, bool locked)
 {
@@ -857,7 +852,7 @@ static int snp_reclaim_cmd_buf(int cmd, void *cmd_buf)
 	return 0;
 }
 
-static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
+int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
 {
 	struct cmd_buf_desc desc_list[CMD_BUF_DESC_MAX] = {0};
 	struct psp_device *psp = psp_master;
-- 
2.51.1