* [PATCH 1/2] MAINTAINERS: Add Dave Hansen as reviewer for INTEL SGX
@ 2021-02-05 15:15 Jarkko Sakkinen
2021-02-05 15:15 ` [PATCH 2/2] x86/sgx: Maintain encl->refcount for each encl->mm_list entry Jarkko Sakkinen
2021-02-06 13:19 ` [tip: x86/sgx] MAINTAINERS: Add Dave Hansen as reviewer for INTEL SGX tip-bot2 for Jarkko Sakkinen
0 siblings, 2 replies; 4+ messages in thread
From: Jarkko Sakkinen @ 2021-02-05 15:15 UTC (permalink / raw
To: sgx
Cc: dave.hansen, Jarkko Sakkinen, Borislav Petkov, Dave Hansen,
linux-kernel
Add Dave as reviewer for INTEL SGX patches.
Cc: Borislav Petkov <bp@alien8.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
MAINTAINERS | 1 +
1 file changed, 1 insertion(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 5b66de2097d6..41b78e20bd1f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9227,6 +9227,7 @@ F: include/linux/tboot.h
INTEL SGX
M: Jarkko Sakkinen <jarkko@kernel.org>
+R: Dave Hansen <dave.hansen@linux.intel.com>
L: linux-sgx@vger.kernel.org
S: Supported
Q: https://patchwork.kernel.org/project/intel-sgx/list/
--
2.30.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/2] x86/sgx: Maintain encl->refcount for each encl->mm_list entry
2021-02-05 15:15 [PATCH 1/2] MAINTAINERS: Add Dave Hansen as reviewer for INTEL SGX Jarkko Sakkinen
@ 2021-02-05 15:15 ` Jarkko Sakkinen
2021-02-06 13:19 ` [tip: x86/sgx] MAINTAINERS: Add Dave Hansen as reviewer for INTEL SGX tip-bot2 for Jarkko Sakkinen
1 sibling, 0 replies; 4+ messages in thread
From: Jarkko Sakkinen @ 2021-02-05 15:15 UTC (permalink / raw
To: sgx
Cc: dave.hansen, Jarkko Sakkinen, Dave Hansen, Haitao Huang,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86,
H. Peter Anvin, Jethro Beekman, Sean Christopherson, linux-sgx,
linux-kernel
This has been shown in tests:
[ +0.000008] WARNING: CPU: 3 PID: 7620 at kernel/rcu/srcutree.c:374 cleanup_srcu_struct+0xed/0x100
There are two functions that drain encl->mm_list:
- sgx_release() (i.e. VFS release) removes the remaining mm_list entries.
- sgx_mmu_notifier_release() removes mm_list entry for the registered
process, if it still exists.
If encl->refcount is taken only for VFS, this can lead to
sgx_encl_release() being executed before sgx_mmu_notifier_release()
completes, which is exactly what happens in the above klog entry.
Each process also needs its own enclave reference.
In order to fix the race condition, increase encl->refcount when an
entry to encl->mm_list added for a process. Release this reference
when the mm_list entry is cleaned up, either in
sgx_mmu_notifier_release() or sgx_release().
Fixes: 1728ab54b4be ("x86/sgx: Add a page reclaimer")
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Reported-by: Haitao Huang <haitao.huang@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
v7:
- Same as v6 but v6 was missing cc to Dave. Thus, also the
MAINTAINERS update.
v6:
- Maintain refcount for each encl->mm_list entry.
v5:
- To make sure that the instance does not get deleted use kref_get()
kref_put(). This also removes the need for additional
synchronize_srcu().
v4:
- Rewrite the commit message.
- Just change the call order. *_expedited() is out of scope for this
bug fix.
v3: Fine-tuned tags, and added missing change log for v2.
v2: Switch to synchronize_srcu_expedited().
arch/x86/kernel/cpu/sgx/driver.c | 6 ++++++
arch/x86/kernel/cpu/sgx/encl.c | 8 ++++++++
2 files changed, 14 insertions(+)
diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
index f2eac41bb4ff..8d8fcc91c0d6 100644
--- a/arch/x86/kernel/cpu/sgx/driver.c
+++ b/arch/x86/kernel/cpu/sgx/driver.c
@@ -72,6 +72,12 @@ static int sgx_release(struct inode *inode, struct file *file)
synchronize_srcu(&encl->srcu);
mmu_notifier_unregister(&encl_mm->mmu_notifier, encl_mm->mm);
kfree(encl_mm);
+
+ /*
+ * Release the mm_list reference, as sgx_mmu_notifier_release()
+ * will only do this only, when it grabs encl_mm.
+ */
+ kref_put(&encl->refcount, sgx_encl_release);
}
kref_put(&encl->refcount, sgx_encl_release);
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index ee50a5010277..c1d9c86c0265 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -474,6 +474,7 @@ static void sgx_mmu_notifier_release(struct mmu_notifier *mn,
if (tmp == encl_mm) {
synchronize_srcu(&encl_mm->encl->srcu);
mmu_notifier_put(mn);
+ kref_put(&encl_mm->encl->refcount, sgx_encl_release);
}
}
@@ -545,6 +546,13 @@ int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm)
}
spin_lock(&encl->mm_lock);
+
+ /*
+ * Take a reference to guarantee that the enclave is not destroyed,
+ * while sgx_mmu_notifier_release() is active.
+ */
+ kref_get(&encl->refcount);
+
list_add_rcu(&encl_mm->list, &encl->mm_list);
/* Pairs with smp_rmb() in sgx_reclaimer_block(). */
smp_wmb();
--
2.30.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 1/2] MAINTAINERS: Add Dave Hansen as reviewer for INTEL SGX
@ 2021-02-05 18:28 Jarkko Sakkinen
0 siblings, 0 replies; 4+ messages in thread
From: Jarkko Sakkinen @ 2021-02-05 18:28 UTC (permalink / raw
To: linux-sgx
Cc: dave.hansen, Jarkko Sakkinen, Borislav Petkov, Dave Hansen,
linux-kernel
Add Dave as reviewer for INTEL SGX patches.
Cc: Borislav Petkov <bp@alien8.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
MAINTAINERS | 1 +
1 file changed, 1 insertion(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 5b66de2097d6..41b78e20bd1f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9227,6 +9227,7 @@ F: include/linux/tboot.h
INTEL SGX
M: Jarkko Sakkinen <jarkko@kernel.org>
+R: Dave Hansen <dave.hansen@linux.intel.com>
L: linux-sgx@vger.kernel.org
S: Supported
Q: https://patchwork.kernel.org/project/intel-sgx/list/
--
2.30.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [tip: x86/sgx] MAINTAINERS: Add Dave Hansen as reviewer for INTEL SGX
2021-02-05 15:15 [PATCH 1/2] MAINTAINERS: Add Dave Hansen as reviewer for INTEL SGX Jarkko Sakkinen
2021-02-05 15:15 ` [PATCH 2/2] x86/sgx: Maintain encl->refcount for each encl->mm_list entry Jarkko Sakkinen
@ 2021-02-06 13:19 ` tip-bot2 for Jarkko Sakkinen
1 sibling, 0 replies; 4+ messages in thread
From: tip-bot2 for Jarkko Sakkinen @ 2021-02-06 13:19 UTC (permalink / raw
To: linux-tip-commits
Cc: Jarkko Sakkinen, Borislav Petkov, Dave Hansen, x86, linux-kernel
The following commit has been merged into the x86/sgx branch of tip:
Commit-ID: 848477782bfa2b6aec738045246abd6cd104006c
Gitweb: https://git.kernel.org/tip/848477782bfa2b6aec738045246abd6cd104006c
Author: Jarkko Sakkinen <jarkko@kernel.org>
AuthorDate: Fri, 05 Feb 2021 17:15:44 +02:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Sat, 06 Feb 2021 14:15:27 +01:00
MAINTAINERS: Add Dave Hansen as reviewer for INTEL SGX
Add Dave as reviewer for INTEL SGX patches.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20210205151546.144810-1-jarkko@kernel.org
---
MAINTAINERS | 1 +
1 file changed, 1 insertion(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 5b66de2..41b78e2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9227,6 +9227,7 @@ F: include/linux/tboot.h
INTEL SGX
M: Jarkko Sakkinen <jarkko@kernel.org>
+R: Dave Hansen <dave.hansen@linux.intel.com>
L: linux-sgx@vger.kernel.org
S: Supported
Q: https://patchwork.kernel.org/project/intel-sgx/list/
^ permalink raw reply related [flat|nested] 4+ messages in thread
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2021-02-06 13:19 ` [tip: x86/sgx] MAINTAINERS: Add Dave Hansen as reviewer for INTEL SGX tip-bot2 for Jarkko Sakkinen
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