Re: [PATCH 7/7] qemu-kvm: Add in-kernel irqchip support for MSI

["Michael S. Tsirkin" <mst@redhat.com>]

On Sat, Apr 23, 2011 at 12:23:40PM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> This adds the required bits to map classic MSI vectors on KVM IRQ
> routing entries and deliver them via the irqchip if enabled.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  hw/msi.c |  111 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/pci.h |    4 ++
>  2 files changed, 115 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/msi.c b/hw/msi.c
> index 3dc3a24..18f683b 100644
> --- a/hw/msi.c
> +++ b/hw/msi.c
> @@ -20,6 +20,7 @@
>  
>  #include "msi.h"
>  #include "range.h"
> +#include "kvm.h"
>  
>  /* Eventually those constants should go to Linux pci_regs.h */
>  #define PCI_MSI_PENDING_32      0x10
> @@ -109,6 +110,92 @@ bool msi_enabled(const PCIDevice *dev)
>           PCI_MSI_FLAGS_ENABLE);
>  }
>  
> +static void kvm_msi_message_from_vector(PCIDevice *dev, unsigned vector,
> +                                        KVMMsiMessage *kmm)
> +{
> +    uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
> +    bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
> +    unsigned int nr_vectors = msi_nr_vectors(flags);
> +
> +    kmm->addr_lo = pci_get_long(dev->config + msi_address_lo_off(dev));
> +    if (msi64bit) {
> +        kmm->addr_hi = pci_get_long(dev->config + msi_address_hi_off(dev));
> +    } else {
> +        kmm->addr_hi = 0;
> +    }
> +
> +    kmm->data = pci_get_word(dev->config + msi_data_off(dev, msi64bit));
> +    if (nr_vectors > 1) {
> +        kmm->data &= ~(nr_vectors - 1);
> +        kmm->data |= vector;
> +    }

msi_notify already has similar logic.
Let's add msi_get_vector_address and msi_get_vector_data


> +}
> +
> +static void kvm_msi_update(PCIDevice *dev)
> +{
> +    uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
> +    unsigned int nr_vectors = msi_nr_vectors(flags);
> +    KVMMsiMessage new_entry, *entry;
> +    bool changed = false;
> +    unsigned int vector;
> +    int r;
> +
> +    for (vector = 0; vector < 32; vector++) {

I'd say up to log_max_vecs: the array is allocated
with nr_vectors.

> +        entry = dev->msi_irq_entries + vector;
> +
> +        if (vector >= nr_vectors) {
> +            if (vector < dev->msi_entries_nr) {
> +                kvm_msi_message_del(entry);
> +                changed = true;
> +            }
> +        } else if (vector >= dev->msi_entries_nr) {
> +            kvm_msi_message_from_vector(dev, vector, entry);
> +            r = kvm_msi_message_add(entry);
> +            if (r) {
> +                fprintf(stderr, "%s: kvm_msi_add failed: %s\n", __func__,
> +                        strerror(-r));
> +                exit(1);
> +            }
> +            changed = true;
> +        } else {
> +            kvm_msi_message_from_vector(dev, vector, &new_entry);
> +            r = kvm_msi_message_update(entry, &new_entry);
> +            if (r < 0) {
> +                fprintf(stderr, "%s: kvm_update_msi failed: %s\n",
> +                        __func__, strerror(-r));
> +                exit(1);
> +            }
> +            if (r > 0) {
> +                *entry = new_entry;
> +                changed = true;
> +            }
> +        }
> +    }
> +    dev->msi_entries_nr = nr_vectors;
> +    if (changed) {
> +        r = kvm_commit_irq_routes();
> +        if (r) {
> +            fprintf(stderr, "%s: kvm_commit_irq_routes failed: %s\n", __func__,
> +                    strerror(-r));
> +            exit(1);
> +        }
> +    }
> +}
> +
> +/* KVM specific MSI helpers */
> +static void kvm_msi_free(PCIDevice *dev)
> +{
> +    unsigned int vector;
> +
> +    for (vector = 0; vector < dev->msi_entries_nr; ++vector) {
> +        kvm_msi_message_del(&dev->msi_irq_entries[vector]);
> +    }
> +    if (dev->msi_entries_nr > 0) {
> +        kvm_commit_irq_routes();
> +    }
> +    dev->msi_entries_nr = 0;
> +}
> +
>  int msi_init(struct PCIDevice *dev, uint8_t offset,
>               unsigned int nr_vectors, bool msi64bit, bool msi_per_vector_mask)
>  {
> @@ -159,6 +246,12 @@ int msi_init(struct PCIDevice *dev, uint8_t offset,
>          pci_set_long(dev->wmask + msi_mask_off(dev, msi64bit),
>                       0xffffffff >> (PCI_MSI_VECTORS_MAX - nr_vectors));
>      }
> +
> +    if (kvm_enabled() && kvm_irqchip_in_kernel()) {
> +        dev->msi_irq_entries = qemu_malloc(nr_vectors *
> +                                           sizeof(*dev->msix_irq_entries));
> +    }
> +
>      return config_offset;
>  }
>  
> @@ -166,6 +259,11 @@ void msi_uninit(struct PCIDevice *dev)
>  {
>      uint16_t flags = pci_get_word(dev->config + msi_flags_off(dev));
>      uint8_t cap_size = msi_cap_sizeof(flags);
> +
> +    if (kvm_enabled() && kvm_irqchip_in_kernel()) {
> +        kvm_msi_free(dev);
> +        qemu_free(dev->msi_irq_entries);
> +    }
>      pci_del_capability(dev, PCI_CAP_ID_MSIX, cap_size);
>      MSI_DEV_PRINTF(dev, "uninit\n");
>  }
> @@ -175,6 +273,10 @@ void msi_reset(PCIDevice *dev)
>      uint16_t flags;
>      bool msi64bit;
>  
> +    if (kvm_enabled() && kvm_irqchip_in_kernel()) {
> +        kvm_msi_free(dev);
> +    }
> +
>      flags = pci_get_word(dev->config + msi_flags_off(dev));
>      flags &= ~(PCI_MSI_FLAGS_QSIZE | PCI_MSI_FLAGS_ENABLE);
>      msi64bit = flags & PCI_MSI_FLAGS_64BIT;
> @@ -224,6 +326,11 @@ void msi_notify(PCIDevice *dev, unsigned int vector)
>          return;
>      }
>  
> +    if (kvm_enabled() && kvm_irqchip_in_kernel()) {
> +        kvm_set_irq(dev->msi_irq_entries[vector].gsi, 1, NULL);
> +        return;
> +    }
> +
>      if (msi64bit) {
>          address = pci_get_quad(dev->config + msi_address_lo_off(dev));
>      } else {
> @@ -312,6 +419,10 @@ void msi_write_config(PCIDevice *dev, uint32_t addr, uint32_t val, int len)
>          pci_set_word(dev->config + msi_flags_off(dev), flags);
>      }
>  
> +    if (kvm_enabled() && kvm_irqchip_in_kernel()) {
> +        kvm_msi_update(dev);
> +    }
> +

Does this ignore per vector masking then?

>      if (!msi_per_vector_mask) {
>          /* if per vector masking isn't supported,
>             there is no pending interrupt. */
> diff --git a/hw/pci.h b/hw/pci.h
> index dc5df17..1a18bc8 100644
> --- a/hw/pci.h
> +++ b/hw/pci.h
> @@ -195,6 +195,10 @@ struct PCIDevice {
>      ram_addr_t rom_offset;
>      uint32_t rom_bar;
>  
> +    /* MSI entries */
> +    int msi_entries_nr;
> +    struct KVMMsiMessage *msi_irq_entries;
> +
>      /* How much space does an MSIX table need. */
>      /* The spec requires giving the table structure
>       * a 4K aligned region all by itself. Align it to
> -- 
> 1.7.1