Re: [PATCH v2 1/8] KVM: extend in-kernel mmio to handle >8 byte transactions

[Wei Xu <wexu2@cisco.com>]

Avi,

Really appreciate your help! Anything if you need help let me know. I am
working on qemu-kvm now and willing to help out...

Wei Xu


On 3/29/11 5:53 AM, "Avi Kivity" <avi@redhat.com> wrote:

> Needed for coalesced mmio using sse.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
>  arch/x86/kvm/x86.c |   58 +++++++++++++++++++++++++++++++++++++++++----------
>  1 files changed, 46 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index bfd7763..e6bcc97 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3596,20 +3596,43 @@ static void kvm_init_msr_list(void)
>  static int vcpu_mmio_write(struct kvm_vcpu *vcpu, gpa_t addr, int len,
>   const void *v)
>  {
> - if (vcpu->arch.apic &&
> -     !kvm_iodevice_write(&vcpu->arch.apic->dev, addr, len, v))
> -  return 0;
> + int handled = 0;
> + int n;
> +
> + do {
> +  n = min(len, 8);
> +  if (!(vcpu->arch.apic &&
> +        !kvm_iodevice_write(&vcpu->arch.apic->dev, addr, n, v))
> +      && kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, n, v))
> +   break;
> +  handled += n;
> +  addr += n;
> +  len -= n;
> +  v += n;
> + } while (len);
>  
> - return kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, len, v);
> + return handled;
>  }
>  
>  static int vcpu_mmio_read(struct kvm_vcpu *vcpu, gpa_t addr, int len, void
> *v)
>  {
> - if (vcpu->arch.apic &&
> -     !kvm_iodevice_read(&vcpu->arch.apic->dev, addr, len, v))
> -  return 0;
> + int handled = 0;
> + int n;
> +
> + do {
> +  n = min(len, 8);
> +  if (!(vcpu->arch.apic &&
> +        !kvm_iodevice_read(&vcpu->arch.apic->dev, addr, n, v))
> +      && kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, n, v))
> +   break;
> +  trace_kvm_mmio(KVM_TRACE_MMIO_READ, n, addr, *(u64 *)v);
> +  handled += n;
> +  addr += n;
> +  len -= n;
> +  v += n;
> + } while (len);
>  
> - return kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, len, v);
> + return handled;
>  }
>  
>  static void kvm_set_segment(struct kvm_vcpu *vcpu,
> @@ -3769,6 +3792,7 @@ static int emulator_read_emulated(unsigned long addr,
>  struct kvm_vcpu *vcpu)
>  {
> gpa_t                 gpa;
> + int handled;
>  
> if (vcpu->mmio_read_completed) {
> memcpy(val, vcpu->mmio_data, bytes);
> @@ -3795,10 +3819,14 @@ mmio:
> /*
> * Is this MMIO handled locally?
> */
> - if (!vcpu_mmio_read(vcpu, gpa, bytes, val)) {
> -  trace_kvm_mmio(KVM_TRACE_MMIO_READ, bytes, gpa, *(u64 *)val);
> + handled = vcpu_mmio_read(vcpu, gpa, bytes, val);
> +
> + if (handled == bytes)
> return X86EMUL_CONTINUE;
> - }
> +
> + gpa += handled;
> + bytes -= handled;
> + val += handled;
>  
> trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, bytes, gpa, 0);
>  
> @@ -3830,6 +3858,7 @@ static int emulator_write_emulated_onepage(unsigned long
> addr,
>   struct kvm_vcpu *vcpu)
>  {
> gpa_t                 gpa;
> + int handled;
>  
> gpa = kvm_mmu_gva_to_gpa_write(vcpu, addr, exception);
>  
> @@ -3848,9 +3877,14 @@ mmio:
> /*
> * Is this MMIO handled locally?
> */
> - if (!vcpu_mmio_write(vcpu, gpa, bytes, val))
> + handled = vcpu_mmio_write(vcpu, gpa, bytes, val);
> + if (handled == bytes)
> return X86EMUL_CONTINUE;
>  
> + gpa += handled;
> + bytes -= handled;
> + val += handled;
> +
> vcpu->mmio_needed = 1;
> vcpu->run->exit_reason = KVM_EXIT_MMIO;
> vcpu->run->mmio.phys_addr = vcpu->mmio_phys_addr = gpa;