linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH] powerpc/svm: Don't issue ultracalls if !mem_encrypt_active()
@ 2021-07-30 11:42 Will Deacon
  2021-08-02  2:03 ` Nicholas Piggin
  2021-08-02 11:20 ` Michael Ellerman
  0 siblings, 2 replies; 4+ messages in thread
From: Will Deacon @ 2021-07-30 11:42 UTC (permalink / raw)
  To: linux-kernel
  Cc: iommu, linuxppc-dev, Will Deacon, Konrad Rzeszutek Wilk,
	Claire Chang, Christoph Hellwig, Robin Murphy, Nicholas Piggin,
	Sachin Sant, Nathan Chancellor

Commit ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
introduced a set_memory_encrypted() call to swiotlb_exit() so that the
buffer pages are returned to an encrypted state prior to being freed.

Sachin reports that this leads to the following crash on a Power server:

[    0.010799] software IO TLB: tearing down default memory pool
[    0.010805] ------------[ cut here ]------------
[    0.010808] kernel BUG at arch/powerpc/kernel/interrupt.c:98!

Nick spotted that this is because set_memory_encrypted() is issuing an
ultracall which doesn't exist for the processor, and should therefore
be gated by mem_encrypt_active() to mirror the x86 implementation.

Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Claire Chang <tientzu@chromium.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Fixes: ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
Suggested-by: Nicholas Piggin <npiggin@gmail.com>
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/1905CD70-7656-42AE-99E2-A31FC3812EAC@linux.vnet.ibm.com/
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/powerpc/platforms/pseries/svm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/svm.c b/arch/powerpc/platforms/pseries/svm.c
index 1d829e257996..87f001b4c4e4 100644
--- a/arch/powerpc/platforms/pseries/svm.c
+++ b/arch/powerpc/platforms/pseries/svm.c
@@ -63,6 +63,9 @@ void __init svm_swiotlb_init(void)
 
 int set_memory_encrypted(unsigned long addr, int numpages)
 {
+	if (!mem_encrypt_active())
+		return 0;
+
 	if (!PAGE_ALIGNED(addr))
 		return -EINVAL;
 
@@ -73,6 +76,9 @@ int set_memory_encrypted(unsigned long addr, int numpages)
 
 int set_memory_decrypted(unsigned long addr, int numpages)
 {
+	if (!mem_encrypt_active())
+		return 0;
+
 	if (!PAGE_ALIGNED(addr))
 		return -EINVAL;
 
-- 
2.32.0.554.ge1b32706d8-goog


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] powerpc/svm: Don't issue ultracalls if !mem_encrypt_active()
  2021-07-30 11:42 [PATCH] powerpc/svm: Don't issue ultracalls if !mem_encrypt_active() Will Deacon
@ 2021-08-02  2:03 ` Nicholas Piggin
  2021-08-02 11:20 ` Michael Ellerman
  1 sibling, 0 replies; 4+ messages in thread
From: Nicholas Piggin @ 2021-08-02  2:03 UTC (permalink / raw)
  To: linux-kernel, Will Deacon
  Cc: Christoph Hellwig, iommu, Konrad Rzeszutek Wilk, linuxppc-dev,
	Nathan Chancellor, Robin Murphy, Sachin Sant, Claire Chang

Excerpts from Will Deacon's message of July 30, 2021 9:42 pm:
> Commit ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
> introduced a set_memory_encrypted() call to swiotlb_exit() so that the
> buffer pages are returned to an encrypted state prior to being freed.
> 
> Sachin reports that this leads to the following crash on a Power server:
> 
> [    0.010799] software IO TLB: tearing down default memory pool
> [    0.010805] ------------[ cut here ]------------
> [    0.010808] kernel BUG at arch/powerpc/kernel/interrupt.c:98!
> 
> Nick spotted that this is because set_memory_encrypted() is issuing an
> ultracall which doesn't exist for the processor, and should therefore
> be gated by mem_encrypt_active() to mirror the x86 implementation.
> 
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Claire Chang <tientzu@chromium.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Fixes: ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
> Suggested-by: Nicholas Piggin <npiggin@gmail.com>
> Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
> Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
> Tested-by: Nathan Chancellor <nathan@kernel.org>
> Link: https://lore.kernel.org/r/1905CD70-7656-42AE-99E2-A31FC3812EAC@linux.vnet.ibm.com/
> Signed-off-by: Will Deacon <will@kernel.org>
> ---

Thanks for writing it.

Acked-by: Nicholas Piggin <npiggin@gmail.com>

>  arch/powerpc/platforms/pseries/svm.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/powerpc/platforms/pseries/svm.c b/arch/powerpc/platforms/pseries/svm.c
> index 1d829e257996..87f001b4c4e4 100644
> --- a/arch/powerpc/platforms/pseries/svm.c
> +++ b/arch/powerpc/platforms/pseries/svm.c
> @@ -63,6 +63,9 @@ void __init svm_swiotlb_init(void)
>  
>  int set_memory_encrypted(unsigned long addr, int numpages)
>  {
> +	if (!mem_encrypt_active())
> +		return 0;
> +
>  	if (!PAGE_ALIGNED(addr))
>  		return -EINVAL;
>  
> @@ -73,6 +76,9 @@ int set_memory_encrypted(unsigned long addr, int numpages)
>  
>  int set_memory_decrypted(unsigned long addr, int numpages)
>  {
> +	if (!mem_encrypt_active())
> +		return 0;
> +
>  	if (!PAGE_ALIGNED(addr))
>  		return -EINVAL;
>  
> -- 
> 2.32.0.554.ge1b32706d8-goog
> 
> 

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] powerpc/svm: Don't issue ultracalls if !mem_encrypt_active()
  2021-07-30 11:42 [PATCH] powerpc/svm: Don't issue ultracalls if !mem_encrypt_active() Will Deacon
  2021-08-02  2:03 ` Nicholas Piggin
@ 2021-08-02 11:20 ` Michael Ellerman
  2021-08-13 16:54   ` Borislav Petkov
  1 sibling, 1 reply; 4+ messages in thread
From: Michael Ellerman @ 2021-08-02 11:20 UTC (permalink / raw)
  To: Will Deacon, linux-kernel, Konrad Rzeszutek Wilk
  Cc: Sachin Sant, linuxppc-dev, Robin Murphy, Nicholas Piggin,
	Nathan Chancellor, iommu, Claire Chang, Will Deacon,
	Christoph Hellwig

Will Deacon <will@kernel.org> writes:
> Commit ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
> introduced a set_memory_encrypted() call to swiotlb_exit() so that the
> buffer pages are returned to an encrypted state prior to being freed.
>
> Sachin reports that this leads to the following crash on a Power server:
>
> [    0.010799] software IO TLB: tearing down default memory pool
> [    0.010805] ------------[ cut here ]------------
> [    0.010808] kernel BUG at arch/powerpc/kernel/interrupt.c:98!
>
> Nick spotted that this is because set_memory_encrypted() is issuing an
> ultracall which doesn't exist for the processor, and should therefore
> be gated by mem_encrypt_active() to mirror the x86 implementation.
>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Claire Chang <tientzu@chromium.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Fixes: ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
> Suggested-by: Nicholas Piggin <npiggin@gmail.com>
> Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
> Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
> Tested-by: Nathan Chancellor <nathan@kernel.org>
> Link: https://lore.kernel.org/r/1905CD70-7656-42AE-99E2-A31FC3812EAC@linux.vnet.ibm.com/
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  arch/powerpc/platforms/pseries/svm.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Thanks.

Acked-by: Michael Ellerman <mpe@ellerman.id.au>


I assume Konrad will take this via the swiotlb tree?

cheers

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] powerpc/svm: Don't issue ultracalls if !mem_encrypt_active()
  2021-08-02 11:20 ` Michael Ellerman
@ 2021-08-13 16:54   ` Borislav Petkov
  0 siblings, 0 replies; 4+ messages in thread
From: Borislav Petkov @ 2021-08-13 16:54 UTC (permalink / raw)
  To: Michael Ellerman, Konrad Rzeszutek Wilk
  Cc: Will Deacon, linux-kernel, Sachin Sant, linuxppc-dev,
	Robin Murphy, Nicholas Piggin, Nathan Chancellor, iommu,
	Claire Chang, Christoph Hellwig, Tom Lendacky

On Mon, Aug 02, 2021 at 09:20:30PM +1000, Michael Ellerman wrote:
> Will Deacon <will@kernel.org> writes:
> > Commit ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
> > introduced a set_memory_encrypted() call to swiotlb_exit() so that the
> > buffer pages are returned to an encrypted state prior to being freed.
> >
> > Sachin reports that this leads to the following crash on a Power server:
> >
> > [    0.010799] software IO TLB: tearing down default memory pool
> > [    0.010805] ------------[ cut here ]------------
> > [    0.010808] kernel BUG at arch/powerpc/kernel/interrupt.c:98!
> >
> > Nick spotted that this is because set_memory_encrypted() is issuing an
> > ultracall which doesn't exist for the processor, and should therefore
> > be gated by mem_encrypt_active() to mirror the x86 implementation.
> >
> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > Cc: Claire Chang <tientzu@chromium.org>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Robin Murphy <robin.murphy@arm.com>
> > Fixes: ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
> > Suggested-by: Nicholas Piggin <npiggin@gmail.com>
> > Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
> > Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
> > Tested-by: Nathan Chancellor <nathan@kernel.org>
> > Link: https://lore.kernel.org/r/1905CD70-7656-42AE-99E2-A31FC3812EAC@linux.vnet.ibm.com/
> > Signed-off-by: Will Deacon <will@kernel.org>
> > ---
> >  arch/powerpc/platforms/pseries/svm.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> 
> Thanks.
> 
> Acked-by: Michael Ellerman <mpe@ellerman.id.au>
> 
> 
> I assume Konrad will take this via the swiotlb tree?

Btw, we're currently reworking that whole "am I running as a
confidential guest" querying, see:

https://lkml.kernel.org/r/029791b24c6412f9427cfe6ec598156c64395964.1627424774.git.thomas.lendacky@amd.com

for example.

I see Konrad has queued this for 5.15 in his devel/for-linus-5.15 branch
so if he sends it to Linus in the upcoming merge window (right Konrad?)
then I can base the rework ontop, once 5.15-rc1 releases, so that there
are no build breakages...

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-08-13 16:54 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-30 11:42 [PATCH] powerpc/svm: Don't issue ultracalls if !mem_encrypt_active() Will Deacon
2021-08-02  2:03 ` Nicholas Piggin
2021-08-02 11:20 ` Michael Ellerman
2021-08-13 16:54   ` Borislav Petkov

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).