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 <g...@redhat.com>
> ---
> 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) ?
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