From: Christoph Hellwig <hch@lst.de>
To: Ashish Kalra <Ashish.Kalra@amd.com>
Cc: konrad.wilk@oracle.com, hch@lst.de, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org,
luto@kernel.org, peterz@infradead.org,
dave.hansen@linux-intel.com, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, brijesh.singh@amd.com,
Thomas.Lendacky@amd.com, jon.grimm@amd.com, rientjes@google.com
Subject: Re: [PATCH v5] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.
Date: Thu, 19 Nov 2020 08:54:22 +0100 [thread overview]
Message-ID: <20201119075422.GA15840@lst.de> (raw)
In-Reply-To: <20201118201243.18510-1-Ashish.Kalra@amd.com>
On Wed, Nov 18, 2020 at 08:12:43PM +0000, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@amd.com>
>
> For SEV, all DMA to and from guest has to use shared
> (un-encrypted) pages. SEV uses SWIOTLB to make this
> happen without requiring changes to device drivers.
> However, depending on workload being run, the default
> 64MB of SWIOTLB might not be enough and SWIOTLB
> may run out of buffers to use for DMA, resulting
> in I/O errors and/or performance degradation for
> high I/O workloads.
FYI, you can use up 73 chars for your commit log. This looks rather
compressed.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Ashish Kalra <Ashish.Kalra@amd.com>
Cc: Thomas.Lendacky@amd.com, jon.grimm@amd.com,
brijesh.singh@amd.com, dave.hansen@linux-intel.com,
konrad.wilk@oracle.com, peterz@infradead.org, x86@kernel.org,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
mingo@redhat.com, bp@alien8.de, luto@kernel.org, hpa@zytor.com,
rientjes@google.com, tglx@linutronix.de, hch@lst.de
Subject: Re: [PATCH v5] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.
Date: Thu, 19 Nov 2020 08:54:22 +0100 [thread overview]
Message-ID: <20201119075422.GA15840@lst.de> (raw)
In-Reply-To: <20201118201243.18510-1-Ashish.Kalra@amd.com>
On Wed, Nov 18, 2020 at 08:12:43PM +0000, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@amd.com>
>
> For SEV, all DMA to and from guest has to use shared
> (un-encrypted) pages. SEV uses SWIOTLB to make this
> happen without requiring changes to device drivers.
> However, depending on workload being run, the default
> 64MB of SWIOTLB might not be enough and SWIOTLB
> may run out of buffers to use for DMA, resulting
> in I/O errors and/or performance degradation for
> high I/O workloads.
FYI, you can use up 73 chars for your commit log. This looks rather
compressed.
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next prev parent reply other threads:[~2020-11-19 7:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 20:12 [PATCH v5] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests Ashish Kalra
2020-11-18 20:12 ` Ashish Kalra
2020-11-18 22:39 ` Borislav Petkov
2020-11-18 22:39 ` Borislav Petkov
2020-11-19 7:54 ` Christoph Hellwig [this message]
2020-11-19 7:54 ` Christoph Hellwig
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