On Fri, Nov 05, 2010 at 01:39:18PM +0800, Xiao Guangrong wrote: > On 11/04/2010 06:35 PM, Gleb Natapov wrote: > > On Thu, Nov 04, 2010 at 06:32:42PM +0800, Xiao Guangrong wrote: > >> nonpaing guest's 'direct_map' is also true, retry #PF for those > >> guests is useless, so use 'tdp_enabled' instead > >> > > nonpaging guest will not attempt async pf. > > Ah, my mistake, but why we can not attempt async pf for nonpaging guest? > We can, but we do not expect to run many nonpaging guests I guess :) > > And by checking tdp_enabled > > here instead of direct_map we will screw nested ntp. > > > > It looks like something broken: apfs can generated in L2 guest (nested ntp guest) > and be retried in L1 guest. > Why is this a problem? apf will be generate on direct map even when L2 guest is running so it should be OK to prefault it into direct map on completion. > Below patch fix it and let nonpaging guest support async pf. I'll post it properly > if you like. :-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 7f20f2c..606978e 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -600,6 +600,7 @@ struct kvm_x86_ops { > struct kvm_arch_async_pf { > u32 token; > gfn_t gfn; > + bool softmmu; > }; > > extern struct kvm_x86_ops *kvm_x86_ops; > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index f3fad4f..48ca312 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -2286,7 +2286,10 @@ static int kvm_handle_bad_page(struct kvm *kvm, gfn_t gfn, pfn_t pfn) > return 1; > } > > -static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn) > +static bool try_async_pf(struct kvm_vcpu *vcpu, bool no_apf, gfn_t gfn, > + gva_t gva, pfn_t *pfn, bool write, bool *writable); > + > +static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn, bool no_apf) > { > int r; > int level; > @@ -2307,7 +2310,9 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn) > > mmu_seq = vcpu->kvm->mmu_notifier_seq; > smp_rmb(); > - pfn = gfn_to_pfn_prot(vcpu->kvm, gfn, write, &map_writable); > + > + if (try_async_pf(vcpu, no_apf, gfn, v, &pfn, write, &map_writable)) > + return 0; > > /* mmio */ > if (is_error_pfn(pfn)) > @@ -2594,7 +2599,7 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva, > gfn = gva >> PAGE_SHIFT; > > return nonpaging_map(vcpu, gva & PAGE_MASK, > - error_code & PFERR_WRITE_MASK, gfn); > + error_code & PFERR_WRITE_MASK, gfn, no_apf); > } > > static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn) > @@ -2602,6 +2607,7 @@ static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn) > struct kvm_arch_async_pf arch; > arch.token = (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; > arch.gfn = gfn; > + arch.softmmu = mmu_is_softmmu(vcpu); > > return kvm_setup_async_pf(vcpu, gva, gfn, &arch); > } > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 2044302..d826d78 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6172,9 +6172,10 @@ EXPORT_SYMBOL_GPL(kvm_set_rflags); > > void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) > { > + bool softmmu = mmu_is_softmmu(vcpu); > int r; > > - if (!vcpu->arch.mmu.direct_map || is_error_page(work->page)) > + if (softmmu || work->arch.softmmu || is_error_page(work->page)) > return; > > r = kvm_mmu_reload(vcpu); > diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h > index 2cea414..48796c7 100644 > --- a/arch/x86/kvm/x86.h > +++ b/arch/x86/kvm/x86.h > @@ -55,6 +55,11 @@ static inline bool mmu_is_nested(struct kvm_vcpu *vcpu) > return vcpu->arch.walk_mmu == &vcpu->arch.nested_mmu; > } > > +static inline bool mmu_is_softmmu(struct kvm_vcpu *vcpu) > +{ > + return !tdp_enabled || mmu_is_nested(vcpu); > +} > + > static inline int is_pae(struct kvm_vcpu *vcpu) > { > return kvm_read_cr4_bits(vcpu, X86_CR4_PAE); -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html