From: Jason Gunthorpe <jgg@ziepe.ca>
To: Dmytro Maluka <dmaluka@chromium.org>
Cc: David Woodhouse <dwmw2@infradead.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
linux-kernel@vger.kernel.org,
"Vineeth Pillai (Google)" <vineeth@bitbyteword.org>,
Aashish Sharma <aashish@aashishsharma.net>,
Grzegorz Jaszczyk <jaszczyk@chromium.org>,
Chuanxiao Dong <chuanxiao.dong@intel.com>,
Kevin Tian <kevin.tian@intel.com>
Subject: Re: [PATCH v2 0/5] iommu/vt-d: Ensure memory ordering in context & root entry updates
Date: Tue, 6 Jan 2026 12:45:18 -0400 [thread overview]
Message-ID: <20260106164518.GA340082@ziepe.ca> (raw)
In-Reply-To: <aV0vM9ad-4QhCNaA@mitya-t14-2025>
On Tue, Jan 06, 2026 at 04:50:11PM +0100, Dmytro Maluka wrote:
> So we'd better make sure that if it happens before the barrier (i.e.
> when the device is not supposed to do DMA), the compiler (and thus
> the CPU) doesn't set the present bit, so it stays non-present, so
> the IOMMU will block this unexpected/malicious DMA?
It is true that any write to the dword containing the present bit
(only!) should probably use WRITE_ONCE.
Jason
next prev parent reply other threads:[~2026-01-06 16:45 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-27 17:57 [PATCH v2 0/5] iommu/vt-d: Ensure memory ordering in context & root entry updates Dmytro Maluka
2025-12-27 17:57 ` [PATCH v2 1/5] iommu/vt-d: Sanitize set bits in pasid_set_bits() Dmytro Maluka
2025-12-27 17:57 ` [PATCH v2 2/5] iommu/vt-d: Generalize pasid_set_bits() Dmytro Maluka
2025-12-27 17:57 ` [PATCH v2 3/5] iommu/vt-d: Ensure memory ordering in context entry updates Dmytro Maluka
2025-12-27 17:57 ` [PATCH v2 4/5] iommu/vt-d: Use smp_wmb() before setting context/pasid present bit Dmytro Maluka
2025-12-27 17:57 ` [PATCH v2 5/5] iommu/vt-d: Use WRITE_ONCE for setting root table entries Dmytro Maluka
2026-01-05 18:12 ` [PATCH v2 0/5] iommu/vt-d: Ensure memory ordering in context & root entry updates Jason Gunthorpe
2026-01-05 18:54 ` Dmytro Maluka
2026-01-05 19:14 ` Jason Gunthorpe
2026-01-05 20:05 ` Dmytro Maluka
2026-01-06 0:14 ` Jason Gunthorpe
2026-01-06 7:48 ` Tian, Kevin
2026-01-06 14:40 ` Dmytro Maluka
2026-01-08 2:22 ` Tian, Kevin
2026-01-06 13:51 ` Dmytro Maluka
2026-01-06 14:23 ` Jason Gunthorpe
2026-01-06 15:50 ` Dmytro Maluka
2026-01-06 16:45 ` Jason Gunthorpe [this message]
2026-01-06 17:14 ` Dmytro Maluka
2026-01-08 2:09 ` Tian, Kevin
2026-01-09 6:32 ` Baolu Lu
[not found] ` <BN9PR11MB5276FB0F465DBFB4EE4D742B8C85A@BN9PR11MB5276.namprd11.prod.outlook.com>
2026-01-08 7:00 ` Tian, Kevin
2026-01-06 3:37 ` Baolu Lu
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