Propagate the GPA PTE protection bits on to the GVA PTEs on a KSeg0
fault (except _PAGE_WRITE), rather than always overriding the
protection. This allows dirty page tracking to work in KSeg0 as a clear
dirty bit in the GPA PTE will propagate to the GVA PTEs.
This makes it simpler to use a single kvm_mips_map_page() to obtain both
the main GPA PTE and its buddy (which may be invalid), which also allows
memory regions to be fully accessible when they don't start and end on a
2*PAGE_SIZE boundary.
Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
---
arch/mips/kvm/mmu.c | 49 ++++++++++++++++++++++++----------------------
1 file changed, 26 insertions(+), 23 deletions(-)
diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index 7962eea4ebc3..9cc941864aa8 100644
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c
@@ -769,15 +769,27 @@ void kvm_mips_flush_gva_pt(pgd_t *pgd, enum kvm_mips_flush flags)
}
}
+static pte_t kvm_mips_gpa_pte_to_gva_unmapped(pte_t pte)
+{
+ /*
+ * Don't leak writeable but clean entries from GPA page tables. We don't
+ * want the normal Linux tlbmod handler to handle dirtying when KVM
+ * accesses guest memory.
+ */
+ if (!pte_dirty(pte))
+ pte = pte_wrprotect(pte);
+
+ return pte;
+}
+
/* XXXKYMA: Must be called with interrupts disabled */
int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
struct kvm_vcpu *vcpu,
bool write_fault)
{
unsigned long gpa;
- kvm_pfn_t pfn0, pfn1;
- unsigned long vaddr;
pte_t pte_gpa[2], *ptep_gva;
+ int idx;
if (KVM_GUEST_KSEGX(badvaddr) != KVM_GUEST_KSEG0) {
kvm_err("%s: Invalid BadVaddr: %#lx\n", __func__, badvaddr);
@@ -785,35 +797,26 @@ int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
return -1;
}
- /* Find host PFNs */
-
- gpa = KVM_GUEST_CPHYSADDR(badvaddr & (PAGE_MASK << 1));
- vaddr = badvaddr & (PAGE_MASK << 1);
-
- if (kvm_mips_map_page(vcpu, gpa, write_fault, &pte_gpa[0], NULL) < 0)
- return -1;
-
- if (kvm_mips_map_page(vcpu, gpa | PAGE_SIZE, write_fault, &pte_gpa[1],
- NULL) < 0)
+ /* Get the GPA page table entry */
+ gpa = KVM_GUEST_CPHYSADDR(badvaddr);
+ idx = (badvaddr >> PAGE_SHIFT) & 1;
+ if (kvm_mips_map_page(vcpu, gpa, write_fault, &pte_gpa[idx],
+ &pte_gpa[!idx]) < 0)
return -1;
- pfn0 = pte_pfn(pte_gpa[0]);
- pfn1 = pte_pfn(pte_gpa[1]);
-
- /* Find GVA page table entry */
-
- ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, vaddr);
+ /* Get the GVA page table entry */
+ ptep_gva = kvm_trap_emul_pte_for_gva(vcpu, badvaddr & ~PAGE_SIZE);
if (!ptep_gva) {
- kvm_err("No ptep for gva %lx\n", vaddr);
+ kvm_err("No ptep for gva %lx\n", badvaddr);
return -1;
}
- /* Write host PFNs into GVA page table */
- ptep_gva[0] = pte_mkyoung(pte_mkdirty(pfn_pte(pfn0, PAGE_SHARED)));
- ptep_gva[1] = pte_mkyoung(pte_mkdirty(pfn_pte(pfn1, PAGE_SHARED)));
+ /* Copy a pair of entries from GPA page table to GVA page table */
+ ptep_gva[0] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[0]);
+ ptep_gva[1] = kvm_mips_gpa_pte_to_gva_unmapped(pte_gpa[1]);
/* Invalidate this entry in the TLB, guest kernel ASID only */
- kvm_mips_host_tlb_inv(vcpu, vaddr, false, true);
+ kvm_mips_host_tlb_inv(vcpu, badvaddr, false, true);
return 0;
}
--
git-series 0.8.10
