linux-kernel - Re: [PATCH] iommu/amd: page-specific invalidations for more than one page

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Message-ID: <YG8D5ZjSxZm6tF9v@8bytes.org>
Date:   Thu, 8 Apr 2021 15:23:49 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Nadav Amit <namit@...are.com>
Cc:     Will Deacon <will@...nel.org>, Jiajun Cao <caojiajun@...are.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iommu/amd: page-specific invalidations for more than one
 page

On Thu, Apr 08, 2021 at 10:29:25AM +0000, Nadav Amit wrote:
> In the version that you referred me to, iommu_update_domain_tlb() only
> regards the size of the region to be flushed and disregards the
> alignment:
> 
> +	order   = get_order(domain->flush.end - domain->flush.start);
> +	mask    = (0x1000ULL << order) - 1;
> +	address = ((domain->flush.start & ~mask) | (mask >> 1)) & ~0xfffULL;
> 
> 
> If you need to flush for instance the region between 0x1000-0x5000, this
> version would use the address|mask of 0x1000 (16KB page). The version I
> sent regards the alignment, and since the range is not aligned would use
> address|mask of 0x3000 (32KB page).
> 
> IIUC, IOVA allocations today are aligned in such way, but at least in
> the past (looking on 3.19 for the matter), it was not like always like
> that, which can explain the problems.

Yeah, that make sense and explains the data corruption problems. I will
give your patch a try on one of my test machines and consider it for
v5.13 if all goes well.

Thanks,

	Joerg