KVM: Retry fault before vmentry

When page is swapped in it is mapped into guest memory only after guest
tries to access it again and generate another fault. To save this fault
we can map it immediately since we know that guest is going to access
the page. Do it only when tdp is enabled for now. Shadow paging case is
more complicated. CR[034] and EFER registers should be switched before
doing mapping and then switched back.

Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index c45376dd041..d6b281e989b 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -527,8 +527,8 @@ out_gpte_changed:
  *  Returns: 1 if we need to emulate the instruction, 0 otherwise, or
  *           a negative value on error.
  */
-static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
-                               u32 error_code)
+static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
+                             bool no_apf)
 {
         int write_fault = error_code & PFERR_WRITE_MASK;
         int user_fault = error_code & PFERR_USER_MASK;
@@ -569,7 +569,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
         mmu_seq = vcpu->kvm->mmu_notifier_seq;
         smp_rmb();
 
-        if (try_async_pf(vcpu, walker.gfn, addr, &pfn))
+        if (try_async_pf(vcpu, no_apf, walker.gfn, addr, &pfn))
                 return 0;
 
         /* mmio */