Commit ee0fa693 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: PPC: Use kvm_vcpu_map() to map guest memory to patch dcbz instructions 



Use kvm_vcpu_map() when patching dcbz in guest memory, as a regular GUP
isn't technically sufficient when writing to data in the target pages.
As per Documentation/core-api/pin_user_pages.rst:

      Correct (uses FOLL_PIN calls):
          pin_user_pages()
          write to the data within the pages
          unpin_user_pages()

      INCORRECT (uses FOLL_GET calls):
          get_user_pages()
          write to the data within the pages
          put_page()

As a happy bonus, using kvm_vcpu_{,un}map() takes care of creating a
mapping and marking the page dirty.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Tested-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-75-seanjc@google.com>
parent 17b7dbaf

arch/powerpc/kvm/book3s_pr.c

+6 −7
Original line number Diff line number Diff line
@@ -639,28 +639,27 @@ static void kvmppc_set_pvr_pr(struct kvm_vcpu *vcpu, u32 pvr) 
 */

static void kvmppc_patch_dcbz(struct kvm_vcpu *vcpu, struct kvmppc_pte *pte)

{

	struct page *hpage;

	struct kvm_host_map map;

	u64 hpage_offset;

	u32 *page;

	int i;

	int i, r;



	hpage = gfn_to_page(vcpu->kvm, pte->raddr >> PAGE_SHIFT);

	if (!hpage)

	r = kvm_vcpu_map(vcpu, pte->raddr >> PAGE_SHIFT, &map);

	if (r)

		return;



	hpage_offset = pte->raddr & ~PAGE_MASK;

	hpage_offset &= ~0xFFFULL;

	hpage_offset /= 4;



	page = kmap_atomic(hpage);

	page = map.hva;



	/* patch dcbz into reserved instruction, so we trap */

	for (i=hpage_offset; i < hpage_offset + (HW_PAGE_SIZE / 4); i++)

		if ((be32_to_cpu(page[i]) & 0xff0007ff) == INS_DCBZ)

			page[i] &= cpu_to_be32(0xfffffff7);



	kunmap_atomic(page);

	put_page(hpage);

	kvm_vcpu_unmap(vcpu, &map);

}



static bool kvmppc_visible_gpa(struct kvm_vcpu *vcpu, gpa_t gpa)