Hi Sheng,
On Tue, Feb 10, 2009 at 05:43:41PM +0800, Sheng Yang wrote:
> One page can be unmapped from userspace, then HVA seems legal, but in fact,
> PFN is illegal.
>
> Signed-off-by: Sheng Yang <sheng@xxxxxxxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 9913a1d..a4fa1b5 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3061,7 +3061,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
> u64 exit_qualification;
> enum emulation_result er;
> gpa_t gpa;
> - unsigned long hva;
> + pfn_t pfn;
> int gla_validity;
> int r;
>
> @@ -3086,8 +3086,8 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
> }
>
> gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
> - hva = gfn_to_hva(vcpu->kvm, gpa >> PAGE_SHIFT);
> - if (!kvm_is_error_hva(hva)) {
> + pfn = gfn_to_pfn(vcpu->kvm, gpa >> PAGE_SHIFT);
> + if (!is_error_pfn(pfn)) {
> r = kvm_mmu_page_fault(vcpu, gpa & PAGE_MASK, 0);
> if (r < 0) {
> printk(KERN_ERR "EPT: Not enough memory!\n");
Forgot to drop the additional reference acquired by gfn_to_pfn ?
Hum, gfn_to_hva assumes the slot information is accurate, which is not
the case if you simply munmap a page in the middle of a slot... we
should provide a helper in userspace, and make sure nothing bad can
happen otherwise.
Anyway, why don't you just let kvm_mmu_page_fault handle instruction
emulation instead of opencoding it in handle_ept_violation ?
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