From b584f460e6d6f1bf968acfcd23aceb663ba996fa Mon Sep 17 00:00:00 2001 From: James Hogan Date: Tue, 6 Dec 2016 14:59:28 +0000 Subject: [PATCH] KVM: MIPS/MMU: Pass GPA PTE bits to KSeg0 GVA PTEs MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org --- 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; } -- 2.25.1