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

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-04-27 15:31, Michael S. Tsirkin wrote:
> 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
> 

Ok.

> 
>> +}
>> +
>> +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.

Right.

> 
>> +        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?

The hook has to be placed here independently.

But, yes, I do not consider to optional mask in kvm_msi_update. Not sure
if it would buy us anything, but it could still be added on top later on.

Jan

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