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KVM: SVM: convert get_user_pages() --> pin_user_pages()

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This code was using get_user_pages*(), in a "Case 2" scenario
(DMA/RDMA), using the categorization from [1]. That means that it's
time to convert the get_user_pages*() + put_page() calls to
pin_user_pages*() + unpin_user_pages() calls.

There is some helpful background in [2]: basically, this is a small
part of fixing a long-standing disconnect between pinning pages, and
file systems' use of those pages.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
    https://lwn.net/Articles/807108/

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Message-Id: <20200526062207.1360225-3-jhubbard@nvidia.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
John Hubbard
2020-05-25 23:22:07 -07:00
committed by Paolo Bonzini
parent 78824fabc7
commit dc42c8ae0a
1 changed files with 3 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/kvm/svm/sev.c
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@@ -348,7 +348,7 @@ static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr,
return NULL;
/* Pin the user virtual address. */
npinned = get_user_pages_fast(uaddr, npages, write ? FOLL_WRITE : 0, pages);
npinned = pin_user_pages_fast(uaddr, npages, write ? FOLL_WRITE : 0, pages);
if (npinned != npages) {
pr_err("SEV: Failure locking %lu pages.\n", npages);
goto err;
@@ -361,7 +361,7 @@ static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr,
err:
if (npinned > 0)
release_pages(pages, npinned);
unpin_user_pages(pages, npinned);
kvfree(pages);
return NULL;
@@ -372,7 +372,7 @@ static void sev_unpin_memory(struct kvm *kvm, struct page **pages,
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
release_pages(pages, npages);
unpin_user_pages(pages, npages);
kvfree(pages);
sev->pages_locked -= npages;
}