KVM: MIPS/T&E: Handle read only GPA in TLB mod

Rewrite TLB modified exception handling to handle read only GPA memory
regions, instead of unconditionally passing the exception to the guest.

If the guest TLB is not the cause of the exception we call into the
normal TLB fault handling depending on the memory segment, which will
soon attempt to remap the physical page to be writable (handling dirty
page tracking or copy on write in the process).

Failing that we fall back to treating it as MMIO, due to a read only
memory region. Once the capability is enabled, this will allow read only
memory regions (such as the Malta boot flash as emulated by QEMU) to
have writes treated as MMIO, while still allowing reads to run
untrapped.

Signed-off-by: James 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

1 files changed, 0 insertions, 5 deletions

diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 17db9d6c7c93..13c9e128bb86 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -614,11 +614,6 @@ extern enum emulation_result kvm_mips_handle_tlbmiss(u32 cause,
 						     struct kvm_vcpu *vcpu,
 						     bool write_fault);
 
-extern enum emulation_result kvm_mips_handle_tlbmod(u32 cause,
-						    u32 *opc,
-						    struct kvm_run *run,
-						    struct kvm_vcpu *vcpu);
-
 extern void kvm_mips_dump_host_tlbs(void);
 extern void kvm_mips_dump_guest_tlbs(struct kvm_vcpu *vcpu);
 extern int kvm_mips_host_tlb_inv(struct kvm_vcpu *vcpu, unsigned long entryhi,