From: Khalid Aziz <khalid.aziz@oracle.com>
To: Christoph Hellwig <hch@lst.de>
Cc: juergh@gmail.com, tycho@tycho.ws, jsteckli@amazon.de,
ak@linux.intel.com, torvalds@linux-foundation.org,
liran.alon@oracle.com, keescook@google.com,
akpm@linux-foundation.org, mhocko@suse.com,
catalin.marinas@arm.com, will.deacon@arm.com, jmorris@namei.org,
konrad.wilk@oracle.com,
Juerg Haefliger <juerg.haefliger@canonical.com>,
deepa.srinivasan@oracle.com, chris.hyser@oracle.com,
tyhicks@canonical.com, dwmw@amazon.co.uk,
andrew.cooper3@citrix.com, jcm@redhat.com,
boris.ostrovsky@oracle.com, kanth.ghatraju@oracle.com,
oao.m.martins@oracle.com, jmattson@google.com,
pradeep.vincent@oracle.com, john.haxby@oracle.com,
tglx@linutronix.de, kirill.shutemov@linux.intel.com,
steven.sistare@oracle.com, labbott@redhat.com, luto@kernel.org,
dave.hansen@intel.com, peterz@infradead.org,
kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Tycho Andersen <tycho@docker.com>
Subject: Re: [RFC PATCH v8 04/14] swiotlb: Map the buffer if it was unmapped by XPFO
Date: Thu, 14 Feb 2019 09:56:24 -0700 [thread overview]
Message-ID: <3c75c46c-2a5a-cd75-83d4-f77d96d22f7d@oracle.com> (raw)
In-Reply-To: <20190214074747.GA10666@lst.de>
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On 2/14/19 12:47 AM, Christoph Hellwig wrote:
> 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.
As I am not the original author of this patch, I am interpreting the
original intent. I think xpfo_page_is_unmapped() was added to account
for kernel build without CONFIG_XPFO. xpfo_page_is_unmapped() has an
alternate definition to return false if CONFIG_XPFO is not defined.
xpfo_is_unmapped() is cleaned up further in patch 11 ("xpfo, mm: remove
dependency on CONFIG_PAGE_EXTENSION") to a one-liner "return
PageXpfoUnmapped(page);". xpfo_is_unmapped() can be eliminated entirely
by adding an else clause to the following code added by that patch:
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -398,6 +402,15 @@ TESTCLEARFLAG(Young, young, PF_ANY)
PAGEFLAG(Idle, idle, PF_ANY)
#endif
+#ifdef CONFIG_XPFO
+PAGEFLAG(XpfoUser, xpfo_user, PF_ANY)
+TESTCLEARFLAG(XpfoUser, xpfo_user, PF_ANY)
+TESTSETFLAG(XpfoUser, xpfo_user, PF_ANY)
+PAGEFLAG(XpfoUnmapped, xpfo_unmapped, PF_ANY)
+TESTCLEARFLAG(XpfoUnmapped, xpfo_unmapped, PF_ANY)
+TESTSETFLAG(XpfoUnmapped, xpfo_unmapped, PF_ANY)
+#endif
+
/*
* On an anonymous page mapped into a user virtual memory area,
* page->mapping points to its anon_vma, not to a struct address_space;
Adding the following #else to above conditional:
#else
TESTPAGEFLAG_FALSE(XpfoUser)
TESTPAGEFLAG_FALSE(XpfoUnmapped)
should allow us to eliminate xpfo_is_unmapped(). Right?
Thanks,
Khalid
>
>> +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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next prev parent reply other threads:[~2019-02-14 16:56 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-14 0:01 [RFC PATCH v8 00/14] Add support for eXclusive Page Frame Ownership Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 01/14] mm: add MAP_HUGETLB support to vm_mmap Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 02/14] x86: always set IF before oopsing from page fault Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 03/14] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO) Khalid Aziz
2019-02-14 10:56 ` Peter Zijlstra
2019-02-14 16:15 ` Borislav Petkov
2019-02-14 17:19 ` Khalid Aziz
2019-02-14 17:13 ` Khalid Aziz
2019-02-14 19:08 ` Peter Zijlstra
2019-02-14 19:58 ` Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 04/14] swiotlb: Map the buffer if it was unmapped by XPFO Khalid Aziz
2019-02-14 7:47 ` Christoph Hellwig
2019-02-14 16:56 ` Khalid Aziz [this message]
2019-02-14 17:44 ` Christoph Hellwig
2019-02-14 19:48 ` Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 05/14] arm64/mm: Add support for XPFO Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 06/14] xpfo: add primitives for mapping underlying memory Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 07/14] arm64/mm, xpfo: temporarily map dcache regions Khalid Aziz
2019-02-14 15:54 ` Tycho Andersen
2019-02-14 17:29 ` Khalid Aziz
2019-02-14 23:49 ` Tycho Andersen
2019-02-14 0:01 ` [RFC PATCH v8 08/14] arm64/mm: disable section/contiguous mappings if XPFO is enabled Khalid Aziz
2019-02-15 13:09 ` Mark Rutland
2019-02-15 14:47 ` Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 09/14] mm: add a user_virt_to_phys symbol Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 10/14] lkdtm: Add test for XPFO Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 11/14] xpfo, mm: remove dependency on CONFIG_PAGE_EXTENSION Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 12/14] xpfo, mm: optimize spinlock usage in xpfo_kunmap Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 13/14] xpfo, mm: Defer TLB flushes for non-current CPUs (x86 only) Khalid Aziz
2019-02-14 17:42 ` Dave Hansen
2019-02-14 19:57 ` Khalid Aziz
2019-02-14 0:01 ` [RFC PATCH v8 14/14] xpfo, mm: Optimize XPFO TLB flushes by batching them together Khalid Aziz
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