RE: [PATCH v2 04/11] x86/vmsi: use the newly introduced EOI callbacks

From: Paul Durrant <xadimgnik@gmail.com>
To: "'Roger Pau Monne'" <roger.pau@citrix.com>,
	<xen-devel@lists.xenproject.org>
Cc: "'Jan Beulich'" <jbeulich@suse.com>,
	"'Andrew Cooper'" <andrew.cooper3@citrix.com>,
	"'Wei Liu'" <wl@xen.org>
Subject: RE: [PATCH v2 04/11] x86/vmsi: use the newly introduced EOI callbacks
Date: Wed, 30 Sep 2020 12:57:31 +0100	[thread overview]
Message-ID: <006f01d69720$e14a7830$a3df6890$@xen.org> (raw)
In-Reply-To: <20200930104108.35969-5-roger.pau@citrix.com>

> -----Original Message-----
> From: Roger Pau Monne <roger.pau@citrix.com>
> Sent: 30 September 2020 11:41
> To: xen-devel@lists.xenproject.org
> Cc: Roger Pau Monne <roger.pau@citrix.com>; Jan Beulich <jbeulich@suse.com>; Andrew Cooper
> <andrew.cooper3@citrix.com>; Wei Liu <wl@xen.org>; Paul Durrant <paul@xen.org>
> Subject: [PATCH v2 04/11] x86/vmsi: use the newly introduced EOI callbacks
> 
> Remove the unconditional call to hvm_dpci_msi_eoi in vlapic_handle_EOI
> and instead use the newly introduced EOI callback mechanism in order
> to register a callback for MSI vectors injected from passed through
> devices.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> ---
>  xen/arch/x86/hvm/vlapic.c    |  2 --
>  xen/arch/x86/hvm/vmsi.c      | 36 ++++++++++++++++++++++--------------
>  xen/drivers/passthrough/io.c |  2 +-
>  xen/include/asm-x86/hvm/io.h |  2 +-
>  4 files changed, 24 insertions(+), 18 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
> index 38c62a02e6..8a18b33428 100644
> --- a/xen/arch/x86/hvm/vlapic.c
> +++ b/xen/arch/x86/hvm/vlapic.c
> @@ -496,8 +496,6 @@ void vlapic_handle_EOI(struct vlapic *vlapic, u8 vector)
>      if ( vlapic_test_vector(vector, &vlapic->regs->data[APIC_TMR]) )
>          vioapic_update_EOI(vector);
> 
> -    hvm_dpci_msi_eoi(vector);
> -
>      spin_lock_irqsave(&vlapic->callback_lock, flags);
>      callback = vlapic->callbacks[index].callback;
>      vlapic->callbacks[index].callback = NULL;
> diff --git a/xen/arch/x86/hvm/vmsi.c b/xen/arch/x86/hvm/vmsi.c
> index 7ca19353ab..e192c4c6da 100644
> --- a/xen/arch/x86/hvm/vmsi.c
> +++ b/xen/arch/x86/hvm/vmsi.c
> @@ -44,11 +44,9 @@
>  #include <asm/event.h>
>  #include <asm/io_apic.h>
> 
> -static void vmsi_inj_irq(
> -    struct vlapic *target,
> -    uint8_t vector,
> -    uint8_t trig_mode,
> -    uint8_t delivery_mode)
> +static void vmsi_inj_irq(struct vlapic *target, uint8_t vector,
> +                         uint8_t trig_mode, uint8_t delivery_mode,
> +                         vlapic_eoi_callback_t *callback, void *data)
>  {
>      HVM_DBG_LOG(DBG_LEVEL_VLAPIC, "vmsi_inj_irq: vec %02x trig %d dm %d\n",
>                  vector, trig_mode, delivery_mode);
> @@ -57,17 +55,17 @@ static void vmsi_inj_irq(
>      {
>      case dest_Fixed:
>      case dest_LowestPrio:
> -        vlapic_set_irq(target, vector, trig_mode);
> +        vlapic_set_irq_callback(target, vector, trig_mode, callback, data);
>          break;
>      default:
>          BUG();
>      }
>  }
> 
> -int vmsi_deliver(
> -    struct domain *d, int vector,
> -    uint8_t dest, uint8_t dest_mode,
> -    uint8_t delivery_mode, uint8_t trig_mode)
> +static int vmsi_deliver_callback(struct domain *d, int vector, uint8_t dest,
> +                                 uint8_t dest_mode, uint8_t delivery_mode,
> +                                 uint8_t trig_mode,
> +                                 vlapic_eoi_callback_t *callback, void *data)
>  {
>      struct vlapic *target;
>      struct vcpu *v;
> @@ -78,7 +76,8 @@ int vmsi_deliver(
>          target = vlapic_lowest_prio(d, NULL, 0, dest, dest_mode);
>          if ( target != NULL )
>          {
> -            vmsi_inj_irq(target, vector, trig_mode, delivery_mode);
> +            vmsi_inj_irq(target, vector, trig_mode, delivery_mode, callback,
> +                         data);
>              break;
>          }
>          HVM_DBG_LOG(DBG_LEVEL_VLAPIC, "null MSI round robin: vector=%02x\n",
> @@ -89,8 +88,8 @@ int vmsi_deliver(
>          for_each_vcpu ( d, v )
>              if ( vlapic_match_dest(vcpu_vlapic(v), NULL,
>                                     0, dest, dest_mode) )
> -                vmsi_inj_irq(vcpu_vlapic(v), vector,
> -                             trig_mode, delivery_mode);
> +                vmsi_inj_irq(vcpu_vlapic(v), vector, trig_mode, delivery_mode,
> +                             callback, data);
>          break;
> 
>      default:
> @@ -103,6 +102,14 @@ int vmsi_deliver(
>      return 0;
>  }
> 
> +

Stray blank line

> +int vmsi_deliver(struct domain *d, int vector, uint8_t dest, uint8_t dest_mode,
> +                 uint8_t delivery_mode, uint8_t trig_mode)
> +{
> +    return vmsi_deliver_callback(d, vector, dest, dest_mode, delivery_mode,
> +                                 trig_mode, NULL, NULL);
> +}
> +
>  void vmsi_deliver_pirq(struct domain *d, const struct hvm_pirq_dpci *pirq_dpci)
>  {
>      uint32_t flags = pirq_dpci->gmsi.gflags;
> @@ -119,7 +126,8 @@ void vmsi_deliver_pirq(struct domain *d, const struct hvm_pirq_dpci *pirq_dpci)
> 
>      ASSERT(pirq_dpci->flags & HVM_IRQ_DPCI_GUEST_MSI);
> 
> -    vmsi_deliver(d, vector, dest, dest_mode, delivery_mode, trig_mode);
> +    vmsi_deliver_callback(d, vector, dest, dest_mode, delivery_mode, trig_mode,
> +                          hvm_dpci_msi_eoi, NULL);

I think there are more efficiencies possible here. E.g. if is_hardware_domain(d) is true then hvm_dpci_msi_eoi() will do nothing, so no point in setting up the callback in that case.

  Paul

>  }
> 
>  /* Return value, -1 : multi-dests, non-negative value: dest_vcpu_id */
> diff --git a/xen/drivers/passthrough/io.c b/xen/drivers/passthrough/io.c
> index 536e91ad76..bff0f6628a 100644
> --- a/xen/drivers/passthrough/io.c
> +++ b/xen/drivers/passthrough/io.c
> @@ -874,7 +874,7 @@ static int _hvm_dpci_msi_eoi(struct domain *d,
>      return 0;
>  }
> 
> -void hvm_dpci_msi_eoi(unsigned int vector)
> +void hvm_dpci_msi_eoi(unsigned int vector, void *data)
>  {
>      struct domain *d = current->domain;
> 
> diff --git a/xen/include/asm-x86/hvm/io.h b/xen/include/asm-x86/hvm/io.h
> index b05f619435..759ee486af 100644
> --- a/xen/include/asm-x86/hvm/io.h
> +++ b/xen/include/asm-x86/hvm/io.h
> @@ -158,7 +158,7 @@ struct hvm_hw_stdvga {
>  void stdvga_init(struct domain *d);
>  void stdvga_deinit(struct domain *d);
> 
> -extern void hvm_dpci_msi_eoi(unsigned int vector);
> +void hvm_dpci_msi_eoi(unsigned int vector, void *data);
> 
>  /* Decode a PCI port IO access into a bus/slot/func/reg. */
>  unsigned int hvm_pci_decode_addr(unsigned int cf8, unsigned int addr,
> --
> 2.28.0