Re: [PATCH v2 03/22] KVM: x86: fix broken read emulation spans a page boundary

Avi Kivity
2011-06-29T08:21:28Z

On 06/22/2011 05:29 PM, Xiao Guangrong wrote:
> If the range spans a 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>
> ---
> arch/x86/kvm/x86.c | 41 ++++++++++++++++++++++++++++++++---------
> 1 files changed, 32 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 0b803f0..eb27be4 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3944,14 +3944,13 @@ out:
> }
> EXPORT_SYMBOL_GPL(kvm_write_guest_virt_system);
>
> -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;
> + gpa_t gpa;
> int handled;
>
> if (vcpu->mmio_read_completed) {
> @@ -3971,8 +3970,7 @@ static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt,
> if ((gpa& PAGE_MASK) == APIC_DEFAULT_PHYS_BASE)
> 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;

This doesn't perform the cpl check.

I suggest dropping this part for now and doing it later.

--
error compiling committee.c: too many arguments to function