linux-kernel - Re: [PATCH] powerpc/svm: Don't issue ultracalls if !mem_encrypt

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1627869720.jrkx2xunfl.astroid@bobo.none>
Date:   Mon, 02 Aug 2021 12:03:19 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     linux-kernel@...r.kernel.org, Will Deacon <will@...nel.org>
Cc:     Christoph Hellwig <hch@....de>, iommu@...ts.linux-foundation.org,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        linuxppc-dev@...ts.ozlabs.org,
        Nathan Chancellor <nathan@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Sachin Sant <sachinp@...ux.vnet.ibm.com>,
        Claire Chang <tientzu@...omium.org>
Subject: Re: [PATCH] powerpc/svm: Don't issue ultracalls if
 !mem_encrypt_active()

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@...cle.com>
> Cc: Claire Chang <tientzu@...omium.org>
> Cc: Christoph Hellwig <hch@....de>
> Cc: Robin Murphy <robin.murphy@....com>
> Fixes: ad6c00283163 ("swiotlb: Free tbl memory in swiotlb_exit()")
> Suggested-by: Nicholas Piggin <npiggin@...il.com>
> Reported-by: Sachin Sant <sachinp@...ux.vnet.ibm.com>
> Tested-by: Sachin Sant <sachinp@...ux.vnet.ibm.com>
> Tested-by: Nathan Chancellor <nathan@...nel.org>
> Link: https://lore.kernel.org/r/1905CD70-7656-42AE-99E2-A31FC3812EAC@linux.vnet.ibm.com/
> Signed-off-by: Will Deacon <will@...nel.org>
> ---

Thanks for writing it.

Acked-by: Nicholas Piggin <npiggin@...il.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
> 
>