From: "Jan Beulich" <JBeulich@suse.com>
To: "Juergen Gross" <jgross@suse.com>
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
<iommu@lists.linux-foundation.org>,
"xen-devel" <xen-devel@lists.xenproject.org>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
<linux-kernel@vger.kernel.org>
Subject: Re: [Xen-devel] [PATCH v2 3/3] xen/swiotlb: remember having called xen_create_contiguous_region()
Date: Wed, 29 May 2019 03:57:37 -0600 [thread overview]
Message-ID: <5CEE57910200007800233571@prv1-mh.provo.novell.com> (raw)
In-Reply-To: <20190529090407.1225-4-jgross@suse.com>
>>> On 29.05.19 at 11:04, <jgross@suse.com> wrote:
> @@ -345,8 +346,11 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
> size = 1UL << (order + XEN_PAGE_SHIFT);
>
> if (!WARN_ON((dev_addr + size - 1 > dma_mask) ||
> - range_straddles_page_boundary(phys, size)))
> + range_straddles_page_boundary(phys, size)) &&
> + PageXenRemapped(virt_to_page(vaddr))) {
> xen_destroy_contiguous_region(phys, order);
> + ClearPageXenRemapped(virt_to_page(vaddr));
> + }
To be symmetric with setting the flag only after having made the region
contiguous, and to avoid (perhaps just theoretical) races, wouldn't it be
better to clear the flag before calling xen_destroy_contiguous_region()?
Even better would be a TestAndClear...() operation.
Jan
WARNING: multiple messages have this Message-ID (diff)
From: "Jan Beulich" <JBeulich@suse.com>
To: "Juergen Gross" <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
xen-devel <xen-devel@lists.xenproject.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [Xen-devel] [PATCH v2 3/3] xen/swiotlb: remember having called xen_create_contiguous_region()
Date: Wed, 29 May 2019 03:57:37 -0600 [thread overview]
Message-ID: <5CEE57910200007800233571@prv1-mh.provo.novell.com> (raw)
In-Reply-To: <20190529090407.1225-4-jgross@suse.com>
>>> On 29.05.19 at 11:04, <jgross@suse.com> wrote:
> @@ -345,8 +346,11 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
> size = 1UL << (order + XEN_PAGE_SHIFT);
>
> if (!WARN_ON((dev_addr + size - 1 > dma_mask) ||
> - range_straddles_page_boundary(phys, size)))
> + range_straddles_page_boundary(phys, size)) &&
> + PageXenRemapped(virt_to_page(vaddr))) {
> xen_destroy_contiguous_region(phys, order);
> + ClearPageXenRemapped(virt_to_page(vaddr));
> + }
To be symmetric with setting the flag only after having made the region
contiguous, and to avoid (perhaps just theoretical) races, wouldn't it be
better to clear the flag before calling xen_destroy_contiguous_region()?
Even better would be a TestAndClear...() operation.
Jan
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
WARNING: multiple messages have this Message-ID (diff)
From: "Jan Beulich" <JBeulich@suse.com>
To: "Juergen Gross" <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
xen-devel <xen-devel@lists.xenproject.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [Xen-devel] [PATCH v2 3/3] xen/swiotlb: remember having called xen_create_contiguous_region()
Date: Wed, 29 May 2019 03:57:37 -0600 [thread overview]
Message-ID: <5CEE57910200007800233571@prv1-mh.provo.novell.com> (raw)
In-Reply-To: <20190529090407.1225-4-jgross@suse.com>
>>> On 29.05.19 at 11:04, <jgross@suse.com> wrote:
> @@ -345,8 +346,11 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
> size = 1UL << (order + XEN_PAGE_SHIFT);
>
> if (!WARN_ON((dev_addr + size - 1 > dma_mask) ||
> - range_straddles_page_boundary(phys, size)))
> + range_straddles_page_boundary(phys, size)) &&
> + PageXenRemapped(virt_to_page(vaddr))) {
> xen_destroy_contiguous_region(phys, order);
> + ClearPageXenRemapped(virt_to_page(vaddr));
> + }
To be symmetric with setting the flag only after having made the region
contiguous, and to avoid (perhaps just theoretical) races, wouldn't it be
better to clear the flag before calling xen_destroy_contiguous_region()?
Even better would be a TestAndClear...() operation.
Jan
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2019-05-29 9:57 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-29 9:04 [PATCH v2 0/3] xen/swiotlb: fix an issue and improve swiotlb-xen Juergen Gross
2019-05-29 9:04 ` [Xen-devel] " Juergen Gross
2019-05-29 9:04 ` Juergen Gross
2019-05-29 9:04 ` [PATCH v2 1/3] xen/swiotlb: fix condition for calling xen_destroy_contiguous_region() Juergen Gross
2019-05-29 9:04 ` [Xen-devel] " Juergen Gross
2019-05-29 9:04 ` Juergen Gross
2019-05-29 9:52 ` Jan Beulich
2019-05-29 9:52 ` [Xen-devel] " Jan Beulich
2019-05-29 9:52 ` Jan Beulich
2019-05-29 9:52 ` Jan Beulich
2019-05-29 9:04 ` Juergen Gross
2019-05-29 9:04 ` [PATCH v2 2/3] xen/swiotlb: simplify range_straddles_page_boundary() Juergen Gross
2019-05-29 9:04 ` Juergen Gross
2019-05-29 9:04 ` [Xen-devel] " Juergen Gross
2019-05-29 9:04 ` Juergen Gross
2019-05-29 9:04 ` [PATCH v2 3/3] xen/swiotlb: remember having called xen_create_contiguous_region() Juergen Gross
2019-05-29 9:04 ` Juergen Gross
2019-05-29 9:04 ` [Xen-devel] " Juergen Gross
2019-05-29 9:04 ` Juergen Gross
2019-05-29 9:57 ` Jan Beulich [this message]
2019-05-29 9:57 ` [Xen-devel] " Jan Beulich
2019-05-29 9:57 ` Jan Beulich
2019-05-29 10:21 ` Juergen Gross
2019-05-29 10:21 ` [Xen-devel] " Juergen Gross
2019-05-29 10:21 ` Juergen Gross
2019-05-29 10:21 ` Juergen Gross
2019-05-29 9:57 ` Jan Beulich
2019-05-30 9:04 ` Christoph Hellwig
2019-05-30 9:04 ` Christoph Hellwig
2019-05-30 9:04 ` [Xen-devel] " Christoph Hellwig
2019-05-30 9:04 ` Christoph Hellwig
2019-05-30 12:46 ` Boris Ostrovsky
2019-05-30 12:46 ` [Xen-devel] " Boris Ostrovsky
2019-05-30 12:46 ` Boris Ostrovsky
2019-05-31 11:38 ` Juergen Gross
2019-05-31 11:38 ` [Xen-devel] " Juergen Gross
2019-05-31 11:38 ` Juergen Gross
2019-06-05 8:37 ` Juergen Gross
2019-06-05 8:37 ` [Xen-devel] " Juergen Gross
2019-06-05 8:37 ` Juergen Gross
2019-05-31 11:38 ` Juergen Gross
2019-05-30 12:46 ` Boris Ostrovsky
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