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Message-ID: <20190214074747.GA10666@lst.de>
Date: Thu, 14 Feb 2019 08:47:47 +0100
From: Christoph Hellwig <hch@....de>
To: Khalid Aziz <khalid.aziz@...cle.com>
Cc: juergh@...il.com, tycho@...ho.ws, jsteckli@...zon.de,
ak@...ux.intel.com, torvalds@...ux-foundation.org,
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Juerg Haefliger <juerg.haefliger@...onical.com>,
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Subject: Re: [RFC PATCH v8 04/14] swiotlb: Map the buffer if it was
unmapped by XPFO
On Wed, Feb 13, 2019 at 05:01:27PM -0700, Khalid Aziz wrote:
> +++ b/kernel/dma/swiotlb.c
> @@ -396,8 +396,9 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
> {
> unsigned long pfn = PFN_DOWN(orig_addr);
> unsigned char *vaddr = phys_to_virt(tlb_addr);
> + struct page *page = pfn_to_page(pfn);
>
> - if (PageHighMem(pfn_to_page(pfn))) {
> + if (PageHighMem(page) || xpfo_page_is_unmapped(page)) {
I think this just wants a page_unmapped or similar helper instead of
needing the xpfo_page_is_unmapped check. We actually have quite
a few similar construct in the arch dma mapping code for architectures
that require cache flushing.
> +bool xpfo_page_is_unmapped(struct page *page)
> +{
> + struct xpfo *xpfo;
> +
> + if (!static_branch_unlikely(&xpfo_inited))
> + return false;
> +
> + xpfo = lookup_xpfo(page);
> + if (unlikely(!xpfo) && !xpfo->inited)
> + return false;
> +
> + return test_bit(XPFO_PAGE_UNMAPPED, &xpfo->flags);
> +}
> +EXPORT_SYMBOL(xpfo_page_is_unmapped);
And at least for swiotlb there is no need to export this helper,
as it is always built in.
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