On Tue, Oct 05, 2010 at 04:00:51PM -0300, Marcelo Tosatti wrote:
> On Mon, Oct 04, 2010 at 05:56:31PM +0200, Gleb Natapov wrote:
> > Send async page fault to a PV guest if it accesses swapped out memory.
> > Guest will choose another task to run upon receiving the fault.
> >
> > Allow async page fault injection only when guest is in user mode since
> > otherwise guest may be in non-sleepable context and will not be able
> > to reschedule.
> >
> > Vcpu will be halted if guest will fault on the same page again or if
> > vcpu executes kernel code.
> >
> > Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
> > ---
> > arch/x86/include/asm/kvm_host.h | 3 ++
> > arch/x86/kvm/mmu.c | 1 +
> > arch/x86/kvm/x86.c | 49 ++++++++++++++++++++++++++++++++------
> > include/trace/events/kvm.h | 17 ++++++++----
> > virt/kvm/async_pf.c | 3 +-
> > 5 files changed, 58 insertions(+), 15 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index de31551..2f6fc87 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -419,6 +419,7 @@ struct kvm_vcpu_arch {
> > gfn_t gfns[roundup_pow_of_two(ASYNC_PF_PER_VCPU)];
> > struct gfn_to_hva_cache data;
> > u64 msr_val;
> > + u32 id;
> > } apf;
> > };
> >
> > @@ -594,6 +595,7 @@ struct kvm_x86_ops {
> > };
> >
> > struct kvm_arch_async_pf {
> > + u32 token;
> > gfn_t gfn;
> > };
> >
> > @@ -842,6 +844,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
> > struct kvm_async_pf *work);
> > void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu,
> > struct kvm_async_pf *work);
> > +bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu);
> > extern bool kvm_find_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn);
> >
> > #endif /* _ASM_X86_KVM_HOST_H */
> > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> > index d85fda8..de53cab 100644
> > --- a/arch/x86/kvm/mmu.c
> > +++ b/arch/x86/kvm/mmu.c
> > @@ -2580,6 +2580,7 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
> > 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;
> >
> > return kvm_setup_async_pf(vcpu, gva, gfn, &arch);
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 3e123ab..0e69d37 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -6225,25 +6225,58 @@ static void kvm_del_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn)
> > }
> > }
> >
> > +static int apf_put_user(struct kvm_vcpu *vcpu, u32 val)
> > +{
> > +
> > + return kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.apf.data, &val,
> > + sizeof(val));
> > +}
> > +
> > void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,
> > struct kvm_async_pf *work)
> > {
> > - vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
> > -
> > - if (work == kvm_double_apf)
> > + if (work == kvm_double_apf) {
> > trace_kvm_async_pf_doublefault(kvm_rip_read(vcpu));
> > - else {
> > - trace_kvm_async_pf_not_present(work->gva);
> > -
> > + vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
> > + } else {
> > + trace_kvm_async_pf_not_present(work->arch.token, work->gva);
> > kvm_add_async_pf_gfn(vcpu, work->arch.gfn);
> > +
> > + if (!(vcpu->arch.apf.msr_val & KVM_ASYNC_PF_ENABLED) ||
> > + kvm_x86_ops->get_cpl(vcpu) == 0)
> > + vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
> > + else if (!apf_put_user(vcpu, KVM_PV_REASON_PAGE_NOT_PRESENT)) {
> > + vcpu->arch.fault.error_code = 0;
> > + vcpu->arch.fault.address = work->arch.token;
> > + kvm_inject_page_fault(vcpu);
> > + }
>
> Missed !kvm_event_needs_reinjection(vcpu) ?
This check is done in can_do_async_pf(). We will not get here if event is pending.
--
Gleb.
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