On 06/12/18 00:10, Jim Mattson wrote: > On Mon, Dec 3, 2018 at 1:31 AM KarimAllah Ahmed <[email protected]> wrote: >> >> Copy the VMCS12 directly from guest memory instead of the map->copy->unmap >> sequence. This also avoids using kvm_vcpu_gpa_to_page() and kmap() which >> assumes that there is a "struct page" for guest memory. >> >> Signed-off-by: KarimAllah Ahmed <[email protected]> >> --- >> v3 -> v4: >> - Return VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID on failure (jmattson@) >> v1 -> v2: >> - Massage commit message a bit. >> --- >> arch/x86/kvm/vmx.c | 24 ++++++++++++------------ >> 1 file changed, 12 insertions(+), 12 deletions(-) >> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index b84f230..75817cb 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -9301,20 +9301,22 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu) >> return 1; >> >> if (vmx->nested.current_vmptr != vmptr) { >> - struct vmcs12 *new_vmcs12; >> - struct page *page; >> - page = kvm_vcpu_gpa_to_page(vcpu, vmptr); >> - if (is_error_page(page)) >> - return nested_vmx_failInvalid(vcpu); >> + struct vmcs12 *new_vmcs12 = (struct vmcs12 >> *)__get_free_page(GFP_KERNEL); >> + >> + if (!new_vmcs12 || >> + kvm_read_guest(vcpu->kvm, vmptr, new_vmcs12, >> + sizeof(*new_vmcs12))) { > > Isn't this a lot slower than kmap() when there is a struct page?
It wouldn't be slower if he read directly into cached_vmcs12. However, as it is now, it's doing two reads instead of one. By doing this, the ENOMEM case also disappears. Paolo
