[PATCH v12 73/84] KVM: PPC: Use kvm_vcpu_map() to map guest memory to patch dcbz instructions
From: Sean Christopherson <seanjc@google.com>
Date: 2024-07-26 23:55:10
Also in:
kvm, kvm-riscv, kvmarm, linux-mips, linux-riscv, linuxppc-dev, lkml, loongarch
Subsystem:
kernel virtual machine for powerpc (kvm/powerpc), linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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>
---
arch/powerpc/kvm/book3s_pr.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index ae4757ac0848..393c18958a5b 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c@@ -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)
--
2.46.0.rc1.232.g9752f9e123-goog