Re: [Qemu-devel] [PATCH v3] KVM: Add async pf flag to KVM_GET/SET_VCPU_EVENTS interface

[Paolo Bonzini <pbonzini@redhat.com>]

On 28/06/2017 14:28, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
> 
> This patch adds async page fault flag to KVM_GET/SET_VCPU_EVENTS interface.
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
> ---
> v2 -> v3:
>  * nested_apf for vcpu events
> v1 -> v2:
>  * reuse the pad for async_page_fault
>  * cleanup coding style
> 
>  linux-headers/asm-x86/kvm.h | 3 ++-
>  target/i386/cpu.h           | 1 +
>  target/i386/kvm.c           | 8 ++++++--
>  3 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/linux-headers/asm-x86/kvm.h b/linux-headers/asm-x86/kvm.h
> index c2824d0..27b368b 100644
> --- a/linux-headers/asm-x86/kvm.h
> +++ b/linux-headers/asm-x86/kvm.h
> @@ -287,6 +287,7 @@ struct kvm_reinject_control {
>  #define KVM_VCPUEVENT_VALID_SIPI_VECTOR	0x00000002
>  #define KVM_VCPUEVENT_VALID_SHADOW	0x00000004
>  #define KVM_VCPUEVENT_VALID_SMM		0x00000008
> +#define KVM_VCPUEVENT_VALID_ASYNC_PF 0x00000010
>  
>  /* Interrupt shadow states */
>  #define KVM_X86_SHADOW_INT_MOV_SS	0x01
> @@ -298,7 +299,7 @@ struct kvm_vcpu_events {
>  		__u8 injected;
>  		__u8 nr;
>  		__u8 has_error_code;
> -		__u8 pad;
> +		__u8 nested_apf;
>  		__u32 error_code;
>  	} exception;
>  	struct {
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index cfe825f..90cb692 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1105,6 +1105,7 @@ typedef struct CPUX86State {
>  
>      /* exception/interrupt handling */
>      int error_code;
> +    uint8_t async_page_fault;
>      int exception_is_int;
>      target_ulong exception_next_eip;
>      target_ulong dr[8]; /* debug registers; note dr4 and dr5 are unused */
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index 49b6115..b2405ec 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -2491,8 +2491,8 @@ static int kvm_put_vcpu_events(X86CPU *cpu, int level)
>      events.exception.injected = (env->exception_injected >= 0);
>      events.exception.nr = env->exception_injected;
>      events.exception.has_error_code = env->has_error_code;
> +    events.exception.nested_apf = env->async_page_fault;
>      events.exception.error_code = env->error_code;
> -    events.exception.pad = 0;
>  
>      events.interrupt.injected = (env->interrupt_injected >= 0);
>      events.interrupt.nr = env->interrupt_injected;
> @@ -2531,7 +2531,8 @@ static int kvm_put_vcpu_events(X86CPU *cpu, int level)
>  
>      if (level >= KVM_PUT_RESET_STATE) {
>          events.flags |=
> -            KVM_VCPUEVENT_VALID_NMI_PENDING | KVM_VCPUEVENT_VALID_SIPI_VECTOR;
> +            KVM_VCPUEVENT_VALID_NMI_PENDING | KVM_VCPUEVENT_VALID_SIPI_VECTOR |
> +                    KVM_VCPUEVENT_VALID_ASYNC_PF;
>      }
>  
>      return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_VCPU_EVENTS, &events);
> @@ -2555,6 +2556,9 @@ static int kvm_get_vcpu_events(X86CPU *cpu)
>      env->exception_injected =
>         events.exception.injected ? events.exception.nr : -1;
>      env->has_error_code = events.exception.has_error_code;
> +    if (events.flags & KVM_VCPUEVENT_VALID_ASYNC_PF) {
> +        env->async_page_fault = events.exception.nested_apf;
> +    }
>      env->error_code = events.exception.error_code;
>  
>      env->interrupt_injected =
> 

You are missing the code in machine.c to transmit this (in a new
subsection).  But let's iron out the KVM parts first of all.

Paolo