From: Roman Kisel <romank@linux.microsoft.com>
To: Christoph Hellwig <hch@lst.de>
Cc: aleksander.lobakin@intel.com, andriy.shevchenko@linux.intel.com,
arnd@arndb.de, bp@alien8.de, catalin.marinas@arm.com,
corbet@lwn.net, dakr@kernel.org, dan.j.williams@intel.com,
dave.hansen@linux.intel.com, decui@microsoft.com,
gregkh@linuxfoundation.org, haiyangz@microsoft.com,
hpa@zytor.com, James.Bottomley@HansenPartnership.com,
Jonathan.Cameron@huawei.com, kys@microsoft.com, leon@kernel.org,
lukas@wunner.de, luto@kernel.org, m.szyprowski@samsung.com,
martin.petersen@oracle.com, mingo@redhat.com,
peterz@infradead.org, quic_zijuhu@quicinc.com,
robin.murphy@arm.com, tglx@linutronix.de, wei.liu@kernel.org,
will@kernel.org, iommu@lists.linux.dev,
linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-doc@vger.kernel.org, linux-hyperv@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
x86@kernel.org, apais@microsoft.com, benhill@microsoft.com,
bperkins@microsoft.com, sunilmut@microsoft.com
Subject: Re: [PATCH hyperv-next 6/6] drivers: SCSI: Do not bounce-bufffer for the confidential VMBus
Date: Wed, 9 Apr 2025 08:36:43 -0700 [thread overview]
Message-ID: <d8876120-5478-4d2f-acad-b0a59261bbc5@linux.microsoft.com> (raw)
In-Reply-To: <20250409105332.GB5721@lst.de>
On 4/9/2025 3:53 AM, Christoph Hellwig wrote:
> On Tue, Apr 08, 2025 at 05:08:35PM -0700, Roman Kisel wrote:
>> The device bit that indicates that the device is capable of I/O
>> with private pages lets avoid excessive copying in the Hyper-V
>> SCSI driver.
>>
>> Set that bit equal to the confidential external memory one to
>> not bounce buffer
>
> Drivers have absolutely no business telling this. The need for bounce
> buffering or not is a platform/IOMMU decision and not one specific to
> a certain device or driver.
Seemed to work although I cannot claim nothing is going to be broken
ever. It did appear from the code that one could have this per-device
bit.
As I understand, you're saying this is architecturally broken. Do you
think a broader set of changes would improve the implementation?
>
--
Thank you,
Roman
prev parent reply other threads:[~2025-04-09 15:36 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-09 0:08 [PATCH hyperv-next 0/6] Confidential VMBus Roman Kisel
2025-04-09 0:08 ` [PATCH hyperv-next 1/6] Documentation: hyperv: " Roman Kisel
2025-04-10 16:54 ` ALOK TIWARI
2025-04-10 19:10 ` Roman Kisel
2025-04-25 6:31 ` Wei Liu
2025-04-09 0:08 ` [PATCH hyperv-next 2/6] drivers: hyperv: VMBus protocol version 6.0 Roman Kisel
2025-04-10 17:03 ` ALOK TIWARI
2025-04-09 0:08 ` [PATCH hyperv-next 3/6] arch: hyperv: Get/set SynIC synth.registers via paravisor Roman Kisel
2025-04-09 0:08 ` [PATCH hyperv-next 4/6] arch: x86, drivers: hyperv: Enable confidential VMBus Roman Kisel
2025-04-09 0:08 ` [PATCH hyperv-next 5/6] arch, drivers: Add device struct bitfield to not bounce-buffer Roman Kisel
2025-04-09 10:52 ` Christoph Hellwig
2025-04-09 15:27 ` Roman Kisel
2025-04-09 16:03 ` Robin Murphy
2025-04-09 16:44 ` Roman Kisel
2025-04-09 23:30 ` Dan Williams
2025-04-10 1:16 ` Michael Kelley
2025-04-11 0:03 ` Dan Williams
2025-04-10 7:23 ` Christoph Hellwig
2025-04-10 23:44 ` Jason Gunthorpe
2025-04-10 23:50 ` Jason Gunthorpe
2025-04-10 7:21 ` Christoph Hellwig
2025-04-10 15:16 ` Roman Kisel
2025-04-09 0:08 ` [PATCH hyperv-next 6/6] drivers: SCSI: Do not bounce-bufffer for the confidential VMBus Roman Kisel
2025-04-09 10:53 ` Christoph Hellwig
2025-04-09 15:36 ` Roman Kisel [this message]
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