[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v3 03/10] xen/arm: smmuv3: Ensure queue is read after updating prod pointer
- To: Julien Grall <julien@xxxxxxx>
- From: Rahul Singh <Rahul.Singh@xxxxxxx>
- Date: Mon, 5 Sep 2022 16:49:50 +0000
- Accept-language: en-US
- Arc-authentication-results: i=2; mx.microsoft.com 1; spf=pass (sender ip is 63.35.35.123) smtp.rcpttodomain=lists.xenproject.org smtp.mailfrom=arm.com; dmarc=pass (p=none sp=none pct=100) action=none header.from=arm.com; dkim=pass (signature was verified) header.d=armh.onmicrosoft.com; arc=pass (0 oda=1 ltdi=1 spf=[1,1,smtp.mailfrom=arm.com] dkim=[1,1,header.d=arm.com] dmarc=[1,1,header.from=arm.com])
- Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=arm.com; dmarc=pass action=none header.from=arm.com; dkim=pass header.d=arm.com; arc=none
- Arc-message-signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=astuJcRJ4TaYXeCiH+Cc4vRFAdkcIwqCPz+W13vNrrI=; b=msdKuoGKKlmHak9ZD3AOC4G7tcyVD7f8s/y5aAv5O36ttdwWzyCUzE+g8+fC6lBmTvfUgez+NUdTx3P2TPzaNUzZ/6st8AHvTMMJM2gDIBqj+PaNpo/NRGncWegotRR19sFXg05rnyxHzfr18JOyqAfJwNHGR1WMxGBrDfMbnWmynjv9csPCi9skz9QvsHvqmG57XHKIjf8TEP/I3QG864I9M+BLcsgIcSQIRKLE92aN1IR1/usxm0jmo/XimsSwnjvaQdIFTQsGpB9d3zdw39VbJzCw8XYEUK15mj7W2hnvNSRgLOSibI6gO4Wb/vFAimlbSUVoFAiwuEb3fcwvxw==
- Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=astuJcRJ4TaYXeCiH+Cc4vRFAdkcIwqCPz+W13vNrrI=; b=DNf0pI3JkAzUAC2xanO2n4LCCruLIiX78qeAmkZONjj5n1/ftlVz+9LNgpIvt9jdp62AtHOOAo26sJugPFewXfmdE1iXtzQjBZfL+u9rC+99RNv7uSIV0aL1ZjTydhQ5fMf1k8itRq+nD0IYLBiJYRaGwtGtx4xgok3UoRCOLzWBvgGuyMHpGN/jMAXB8P+PCQxDzl/sWNv1FeTsR4O8HRpd0gxEg2J+G+BtwVUmaFvngxU/AmvVGpu4Hdx+SGRz4uGU2pDeJBZRWjd8OZkgYW1nHmGSmv9wrUzuN1MzY99B2JfSuJ1q9SazTK8CSqMYU+p459Z1l4FPj1EOlcBq3w==
- Arc-seal: i=2; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=pass; b=Ns16w31PCAYT3J3bG8/NiIcq/INHb3WF9w9IiXHq4DcUeqkFOlM05QnfZsnsWEOo+zgW+U3Tn06zQxfvXAhihe0a91HUd8pDIpSl+4jD2hiXMeeGrQOpg3WVCLSO3V8xpv5epT/heNNQ4VPV3Nl6DmfayCqw1tm9dcRb9C/ptu8OCuNV6jBgIdJwaIp327zRabIclAWeNRPA7SyRIvi5LzCpQEXGCS2Gu4EqNM9YYQTDdw5tRRk6kOyXhD/+fq9CEOKpr1UQsc6opomz8VoARzsId4QPqKzIGJHUmGhX+p//mzI6PFZ4WHu7uJt1cIDSaMhHDe6i861ac3j+mdojsA==
- Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=TzrCKBZY/9MBrce+2vLzeXClEjmqas4TAk+MroyGjEgfnfTz5fCQ8/ysqa2RgR7jmvP+iOmI+TY6zZue6sBcZC5Ty7ZhwrM6k51DLJpGvJJZJ67qmZU7QxsJFo7xlkMjz5HWMt3GNm36Gl7X6Tk2Vswy1IvNHdGGn+gciUJ08eZgQLf2YvSM0BqZGxxfsQi9Z3Fn5PxNmGzSPAJC/d0Ln3YKPXBiuzD6723Yv2jVE6S1dpjBo3sWLFyAH+3hX5AbKMOFnTawyYPd6CZYO9dp37HcRNhnBsSJeriy0RGiq+6H+L/imll+aoTSdQ5nUsUmyyz6iRpRbG6ibd1rgArHZQ==
- Authentication-results-original: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com;
- Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Zhou Wang <wangzhou1@xxxxxxxxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Will Deacon <will@xxxxxxxxxx>
- Delivery-date: Mon, 05 Sep 2022 16:50:16 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Nodisclaimer: true
- Original-authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com;
- Thread-index: AQHYwUUf4E2j4BiT+ESEZERmzSI0nK3RCQUAgAADdQA=
- Thread-topic: [PATCH v3 03/10] xen/arm: smmuv3: Ensure queue is read after updating prod pointer
Hi Julien,
> On 5 Sep 2022, at 5:37 pm, Julien Grall <julien@xxxxxxx> wrote:
>
>
>
> On 05/09/2022 17:30, Rahul Singh wrote:
>> From: Zhou Wang <wangzhou1@xxxxxxxxxxxxx>
>> Backport Linux commit a76a37777f2c. Rename __iomb to iomb() while
>> merging to get in sync with other Xen definitions.
>> Reading the 'prod' MMIO register in order to determine whether or
>> not there is valid data beyond 'cons' for a given queue does not
>> provide sufficient dependency ordering, as the resulting access is
>> address dependent only on 'cons' and can therefore be speculated
>> ahead of time, potentially allowing stale data to be read by the
>> CPU.
>> Use readl() instead of readl_relaxed() when updating the shadow copy
>> of the 'prod' pointer, so that all speculated memory reads from the
>> corresponding queue can occur only from valid slots.
>> Signed-off-by: Zhou Wang <wangzhou1@xxxxxxxxxxxxx>
>> Link:
>> https://lore.kernel.org/r/1601281922-117296-1-git-send-email-wangzhou1@xxxxxxxxxxxxx
>> [will: Use readl() instead of explicit barrier. Update 'cons' side to match.]
>> Signed-off-by: Will Deacon <will@xxxxxxxxxx>
>> Origin: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>> a76a37777f2c
>> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
>> ---
>> Changes in v3:
>> - rename __iomb() to iomb() and also move it from common file to
>> smmu-v3.c file
>
> Hmmm... Quoting Bertrand:
>
> "We need the __iomb as “linux compatibility” in fact so I would suggest for
> now to only introduce it at the beginning of smmu-v3.c with other linux
> compatibility stuff to prevent adding this to Xen overall."
>
> Which I also agreed. I couldn't a more recent conversation explaining your
> approach. Can you outline why you didn't follow the approached discussed?
>
I am really sorry that I missed the naming and when I made the patch in my mind
there was a comment from Stefano to
rename the __iomb() to iomb(). I will send only this patch after fixing or do
you want me to send the whole series?
Regards,
Rahul
|
