On Tue, Jun 12, 2012 at 03:01:23PM +0300, Gleb Natapov wrote:
> Current code assumes that IO exit was due to instruction emulation
> and handles execution back to emulator directly. This patch adds new
> userspace IO exit completion callback that can be set by any other code
> that caused IO exit to userspace.
>
> Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/x86.c | 92 +++++++++++++++++++++++----------------
> 2 files changed, 56 insertions(+), 37 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index db7c1f2..1a1bba6 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -406,6 +406,7 @@ struct kvm_vcpu_arch {
> struct x86_emulate_ctxt emulate_ctxt;
> bool emulate_regs_need_sync_to_vcpu;
> bool emulate_regs_need_sync_from_vcpu;
> + int (*complete_userspace_io)(struct kvm_vcpu *vcpu);
>
> gpa_t time;
> struct pvclock_vcpu_time_info hv_clock;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a01a424..6fa0e21 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4547,6 +4547,9 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> return true;
> }
>
> +static int complete_emulated_mmio(struct kvm_vcpu *vcpu);
> +static int complete_emulated_pio(struct kvm_vcpu *vcpu);
> +
> int x86_emulate_instruction(struct kvm_vcpu *vcpu,
> unsigned long cr2,
> int emulation_type,
> @@ -4617,13 +4620,16 @@ restart:
> } else if (vcpu->arch.pio.count) {
> if (!vcpu->arch.pio.in)
> vcpu->arch.pio.count = 0;
> - else
> + else {
> writeback = false;
> + vcpu->arch.complete_userspace_io = complete_emulated_pio;
> + }
> r = EMULATE_DO_MMIO;
> } else if (vcpu->mmio_needed) {
> if (!vcpu->mmio_is_write)
> writeback = false;
> r = EMULATE_DO_MMIO;
> + vcpu->arch.complete_userspace_io = complete_emulated_mmio;
> } else if (r == EMULATION_RESTART)
> goto restart;
> else
> @@ -5474,6 +5480,24 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
> return r;
> }
>
> +static inline int complete_emulated_io(struct kvm_vcpu *vcpu)
> +{
> + int r;
> + vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> + r = emulate_instruction(vcpu, EMULTYPE_NO_DECODE);
> + srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
> + if (r != EMULATE_DONE)
> + return 0;
> + return 1;
> +}
> +
> +static int complete_emulated_pio(struct kvm_vcpu *vcpu)
> +{
> + BUG_ON(!vcpu->arch.pio.count);
> +
> + return complete_emulated_io(vcpu);
> +}
> +
> /*
> * Implements the following, as a state machine:
> *
> @@ -5490,47 +5514,37 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
> * copy data
> * exit
> */
> -static int complete_mmio(struct kvm_vcpu *vcpu)
> +static int complete_emulated_mmio(struct kvm_vcpu *vcpu)
> {
> struct kvm_run *run = vcpu->run;
> struct kvm_mmio_fragment *frag;
> - int r;
>
> - if (!(vcpu->arch.pio.count || vcpu->mmio_needed))
> - return 1;
> + BUG_ON(!vcpu->mmio_needed);
>
> - if (vcpu->mmio_needed) {
> - /* Complete previous fragment */
> - frag = &vcpu->mmio_fragments[vcpu->mmio_cur_fragment++];
> - if (!vcpu->mmio_is_write)
> - memcpy(frag->data, run->mmio.data, frag->len);
> - if (vcpu->mmio_cur_fragment == vcpu->mmio_nr_fragments) {
> - vcpu->mmio_needed = 0;
> - if (vcpu->mmio_is_write)
> - return 1;
> - vcpu->mmio_read_completed = 1;
> - goto done;
> - }
> - /* Initiate next fragment */
> - ++frag;
> - run->exit_reason = KVM_EXIT_MMIO;
> - run->mmio.phys_addr = frag->gpa;
> + /* Complete previous fragment */
> + frag = &vcpu->mmio_fragments[vcpu->mmio_cur_fragment++];
> + if (!vcpu->mmio_is_write)
> + memcpy(frag->data, run->mmio.data, frag->len);
> + if (vcpu->mmio_cur_fragment == vcpu->mmio_nr_fragments) {
> + vcpu->mmio_needed = 0;
> if (vcpu->mmio_is_write)
> - memcpy(run->mmio.data, frag->data, frag->len);
> - run->mmio.len = frag->len;
> - run->mmio.is_write = vcpu->mmio_is_write;
> - return 0;
> -
> - }
> -done:
> - vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> - r = emulate_instruction(vcpu, EMULTYPE_NO_DECODE);
> - srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
> - if (r != EMULATE_DONE)
> - return 0;
> - return 1;
> + return 1;
> + vcpu->mmio_read_completed = 1;
> + return complete_emulated_io(vcpu);
> + }
> + /* Initiate next fragment */
> + ++frag;
> + run->exit_reason = KVM_EXIT_MMIO;
> + run->mmio.phys_addr = frag->gpa;
> + if (vcpu->mmio_is_write)
> + memcpy(run->mmio.data, frag->data, frag->len);
> + run->mmio.len = frag->len;
> + run->mmio.is_write = vcpu->mmio_is_write;
> + vcpu->arch.complete_userspace_io = complete_emulated_mmio;
> + return 0;
> }
>
> +
> int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
> {
> int r;
> @@ -5557,9 +5571,13 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
> }
> }
>
> - r = complete_mmio(vcpu);
> - if (r <= 0)
> - goto out;
> + if (unlikely(vcpu->arch.complete_userspace_io)) {
> + int (*cui)(struct kvm_vcpu *) = vcpu->arch.complete_userspace_io;
> + vcpu->arch.complete_userspace_io = NULL;
> + r = cui(vcpu);
> + if (r <= 0)
< 0 when?
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