linux-kernel - [PATCH] crypto: ccp: Properly unregister /dev/sev on sev PLATFORM

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Message-ID: <20240815122500.71946-1-papaluri@amd.com>
Date: Thu, 15 Aug 2024 07:25:00 -0500
From: Pavan Kumar Paluri <papaluri@....com>
To: <linux-crypto@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, Tom Lendacky <thomas.lendacky@....com>,
	Ashish Kalra <ashish.kalra@....com>, John Allen <john.allen@....com>,
	"Herbert Xu" <herbert@...dor.apana.org.au>, "David S . Miller"
	<davem@...emloft.net>, Pavan Kumar Paluri <papaluri@....com>,
	<stable@...r.kernel.org>
Subject: [PATCH] crypto: ccp: Properly unregister /dev/sev on sev PLATFORM_STATUS failure

In case of sev PLATFORM_STATUS failure, sev_get_api_version() fails
resulting in sev_data field of psp_master nulled out. This later becomes
a problem when unloading the ccp module because the device has not been
unregistered (via misc_deregister()) before clearing the sev_data field
of psp_master. As a result, on reloading the ccp module, a duplicate
device issue is encountered as can be seen from the dmesg log below.

on reloading ccp module via modprobe ccp

Call Trace:
  <TASK>
  dump_stack_lvl+0xd7/0xf0
  dump_stack+0x10/0x20
  sysfs_warn_dup+0x5c/0x70
  sysfs_create_dir_ns+0xbc/0xd
  kobject_add_internal+0xb1/0x2f0
  kobject_add+0x7a/0xe0
  ? srso_alias_return_thunk+0x5/0xfbef5
  ? get_device_parent+0xd4/0x1e0
  ? __pfx_klist_children_get+0x10/0x10
  device_add+0x121/0x870
  ? srso_alias_return_thunk+0x5/0xfbef5
  device_create_groups_vargs+0xdc/0x100
  device_create_with_groups+0x3f/0x60
  misc_register+0x13b/0x1c0
  sev_dev_init+0x1d4/0x290 [ccp]
  psp_dev_init+0x136/0x300 [ccp]
  sp_init+0x6f/0x80 [ccp]
  sp_pci_probe+0x2a6/0x310 [ccp]
  ? srso_alias_return_thunk+0x5/0xfbef5
  local_pci_probe+0x4b/0xb0
  work_for_cpu_fn+0x1a/0x30
  process_one_work+0x203/0x600
  worker_thread+0x19e/0x350
  ? __pfx_worker_thread+0x10/0x10
  kthread+0xeb/0x120
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x3c/0x60
  ? __pfx_kthread+0x10/0x10
  ret_from_fork_asm+0x1a/0x30
  </TASK>
  kobject: kobject_add_internal failed for sev with -EEXIST, don't try to register things with the same name in the same directory.
  ccp 0000:22:00.1: sev initialization failed
  ccp 0000:22:00.1: psp initialization failed
  ccp 0000:a2:00.1: no command queues available
  ccp 0000:a2:00.1: psp enabled

Address this issue by unregistering the /dev/sev before clearing out
sev_data in case of PLATFORM_STATUS failure.

Fixes: 200664d5237f ("crypto: ccp: Add Secure Encrypted Virtualization (SEV) command support")
Cc: stable@...r.kernel.org
Signed-off-by: Pavan Kumar Paluri <papaluri@....com>
---
 drivers/crypto/ccp/sev-dev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 9810edbb272d..5f63d2018649 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -2410,6 +2410,8 @@ void sev_pci_init(void)
 	return;

 err:
+	sev_dev_destroy(psp_master);
+
 	psp_master->sev_data = NULL;
 }

base-commit: b8c7cbc324dc17b9e42379b42603613580bec2d8
-- 
2.34.1