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KVM: x86: fix broken read emulation spans a page boundary

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If the range spans a page boundary, the mmio access can be broke, fix it as
write emulation.

And we already get the guest physical address, so use it to read guest data
directly to avoid walking guest page table again

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Xiao Guangrong 2011-07-13 14:31:08 +08:00 committed by Avi Kivity
parent 9be3be1f15
commit ca7d58f375
1 changed files with 31 additions and 8 deletions
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39
arch/x86/kvm/x86.c
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@ -4045,13 +4045,12 @@ static int vcpu_mmio_gva_to_gpa(struct kvm_vcpu *vcpu, unsigned long gva,
return 0;
}
static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt,
unsigned long addr,
void *val,
unsigned int bytes,
struct x86_exception *exception)
static int emulator_read_emulated_onepage(unsigned long addr,
void *val,
unsigned int bytes,
struct x86_exception *exception,
struct kvm_vcpu *vcpu)
{
struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
gpa_t gpa;
int handled, ret;
@ -4071,8 +4070,7 @@ static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt,
if (ret)
goto mmio;
if (kvm_read_guest_virt(ctxt, addr, val, bytes, exception)
== X86EMUL_CONTINUE)
if (!kvm_read_guest(vcpu->kvm, gpa, val, bytes))
return X86EMUL_CONTINUE;
mmio:
@ -4101,6 +4099,31 @@ mmio:
return X86EMUL_IO_NEEDED;
}
static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt,
unsigned long addr,
void *val,
unsigned int bytes,
struct x86_exception *exception)
{
struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
/* Crossing a page boundary? */
if (((addr + bytes - 1) ^ addr) & PAGE_MASK) {
int rc, now;
now = -addr & ~PAGE_MASK;
rc = emulator_read_emulated_onepage(addr, val, now, exception,
vcpu);
if (rc != X86EMUL_CONTINUE)
return rc;
addr += now;
val += now;
bytes -= now;
}
return emulator_read_emulated_onepage(addr, val, bytes, exception,
vcpu);
}
int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
const void *val, int bytes)
{