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Date:   Mon, 27 Nov 2023 16:59:13 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Petr =?utf-8?B?VGVzYcWZw61r?= <petr@tesarici.cz>
Cc:     Christoph Hellwig <hch@lst.de>, Halil Pasic <pasic@linux.ibm.com>,
        Niklas Schnelle <schnelle@linux.ibm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Petr Tesarik <petr.tesarik1@huawei-partners.com>,
        Ross Lagerwall <ross.lagerwall@citrix.com>,
        linux-pci <linux-pci@vger.kernel.org>,
        linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
        Matthew Rosato <mjrosato@linux.ibm.com>,
        Jianxiong Gao <jxgao@google.com>
Subject: Re: Memory corruption with CONFIG_SWIOTLB_DYNAMIC=y
Message-ID: <20231127155913.GA1468@lst.de>
References: <104a8c8fedffd1ff8a2890983e2ec1c26bff6810.camel@linux.ibm.com> <20231103171447.02759771.pasic@linux.ibm.com> <20231103214831.26d29f4d@meshulam.tesarici.cz> <20231107182420.0bd8c211.pasic@linux.ibm.com> <20231108101347.77cab795@meshulam.tesarici.cz> <20231123111608.17727968@meshulam.tesarici.cz>
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On Thu, Nov 23, 2023 at 11:16:08AM +0100, Petr Tesařík wrote:
> > To sum it up, there are two types of alignment:
> > 
> > 1. specified by a device's min_align_mask; this says how many low
> >    bits of a buffer's physical address must be preserved,
> > 
> > 2. specified by allocation size and/or the alignment parameter;
> >    this says how many low bits in the first IO TLB slot's physical
> >    address must be zero.

Both are correct.