Commit dc42c8ae authored May 25, 2020 by John Hubbard Committed by Paolo Bonzini Jul 08, 2020

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

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>

parent 78824fab

arch/x86/kvm/svm/sev.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -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;
		}

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