Commit b584f460 authored by James Hogan's avatar James Hogan
Browse files

KVM: MIPS/MMU: Pass GPA PTE bits to KSeg0 GVA PTEs 



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: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
parent b5f1dd1b

arch/mips/kvm/mmu.c

+26 −23
Original line number Diff line number Diff line
@@ -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;

}

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