KVM: Fix page-crossing MMIO

MMIO that are split across a page boundary are currently broken - the
code does not expect to be aborted by the exit to userspace for the
first MMIO fragment.

This patch fixes the problem by generalizing the current code for handling
16-byte MMIOs to handle a number of "fragments", and changes the MMIO
code to create those fragments.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

2 files changed, 7 insertions, 5 deletions

diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
index c4b4bac3d09e..6d6a5ac48d85 100644
--- a/arch/ia64/include/asm/kvm_host.h
+++ b/arch/ia64/include/asm/kvm_host.h
@@ -449,6 +449,8 @@ struct kvm_vcpu_arch {
         char log_buf[VMM_LOG_LEN];
         union context host;
         union context guest;
+
+        char mmio_data[8];
 };
 
 struct kvm_vm_stat {
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 9d80ff8d9eff..882ab21a8dcd 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -232,12 +232,12 @@ static int handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
         if ((p->addr & PAGE_MASK) == IOAPIC_DEFAULT_BASE_ADDRESS)
                 goto mmio;
         vcpu->mmio_needed = 1;
-        vcpu->mmio_phys_addr = kvm_run->mmio.phys_addr = p->addr;
-        vcpu->mmio_size = kvm_run->mmio.len = p->size;
+        vcpu->mmio_fragments[0].gpa = kvm_run->mmio.phys_addr = p->addr;
+        vcpu->mmio_fragments[0].len = kvm_run->mmio.len = p->size;
         vcpu->mmio_is_write = kvm_run->mmio.is_write = !p->dir;
 
         if (vcpu->mmio_is_write)
-                memcpy(vcpu->mmio_data, &p->data, p->size);
+                memcpy(vcpu->arch.mmio_data, &p->data, p->size);
         memcpy(kvm_run->mmio.data, &p->data, p->size);
         kvm_run->exit_reason = KVM_EXIT_MMIO;
         return 0;
@@ -719,7 +719,7 @@ static void kvm_set_mmio_data(struct kvm_vcpu *vcpu)
         struct kvm_mmio_req *p = kvm_get_vcpu_ioreq(vcpu);
 
         if (!vcpu->mmio_is_write)
-                memcpy(&p->data, vcpu->mmio_data, 8);
+                memcpy(&p->data, vcpu->arch.mmio_data, 8);
         p->state = STATE_IORESP_READY;
 }
 
@@ -739,7 +739,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
         }
 
         if (vcpu->mmio_needed) {
-                memcpy(vcpu->mmio_data, kvm_run->mmio.data, 8);
+                memcpy(vcpu->arch.mmio_data, kvm_run->mmio.data, 8);
                 kvm_set_mmio_data(vcpu);
                 vcpu->mmio_read_completed = 1;
                 vcpu->mmio_needed = 0;