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

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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: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-75-seanjc@google.com>
This commit is contained in:
Sean Christopherson
2024-10-10 11:24:16 -07:00
committed by Paolo Bonzini
parent 17b7dbaf18
commit ee0fa69354
1 changed files with 6 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
arch/powerpc/kvm/book3s_pr.c
View File

@@ -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)