Re: [Qemu-devel] [PATCH v2 5/6] msix: Allow full specification of MSIX layout

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

On 2012-06-14 06:51, Alex Williamson wrote:
> Finally, complete the fully specified interface.  msix_add_config()
> gets moved to be closer to the setup functions where it's actually
> used.  msix_mmio_setup() gets folded into msix_init().  And
> msix_uninit() gets reworked a bit so we can call it as cleanup
> from msix_init().
> 
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
> 
>  hw/msix.c |  217 +++++++++++++++++++++++++++----------------------------------
>  hw/msix.h |   10 ++-
>  2 files changed, 101 insertions(+), 126 deletions(-)
> 
> diff --git a/hw/msix.c b/hw/msix.c
> index d476d07..047646a 100644
> --- a/hw/msix.c
> +++ b/hw/msix.c
> @@ -27,14 +27,6 @@
>  #define MSIX_ENABLE_MASK (PCI_MSIX_FLAGS_ENABLE >> 8)
>  #define MSIX_MASKALL_MASK (PCI_MSIX_FLAGS_MASKALL >> 8)
>  
> -/* How much space does an MSIX table need. */
> -/* The spec requires giving the table structure
> - * a 4K aligned region all by itself. */
> -#define MSIX_PAGE_SIZE 0x1000
> -/* Reserve second half of the page for pending bits */
> -#define MSIX_PAGE_PENDING (MSIX_PAGE_SIZE / 2)
> -#define MSIX_MAX_ENTRIES 32
> -
>  static MSIMessage msix_get_message(PCIDevice *dev, unsigned vector)
>  {
>      uint8_t *table_entry = dev->msix_table + vector * PCI_MSIX_ENTRY_SIZE;
> @@ -45,47 +37,6 @@ static MSIMessage msix_get_message(PCIDevice *dev, unsigned vector)
>      return msg;
>  }
>  
> -/* Add MSI-X capability to the config space for the device. */
> -/* Given a bar and its size, add MSI-X table on top of it
> - * and fill MSI-X capability in the config space.
> - * Original bar size must be a power of 2 or 0.
> - * New bar size is returned. */
> -static int msix_add_config(struct PCIDevice *pdev, unsigned short nentries,
> -                           unsigned bar_nr, unsigned bar_size)
> -{
> -    int config_offset;
> -    uint8_t *config;
> -
> -    if (nentries < 1 || nentries > PCI_MSIX_FLAGS_QSIZE + 1)
> -        return -EINVAL;
> -    if (bar_size > 0x80000000)
> -        return -ENOSPC;
> -
> -    /* Require aligned offset for MSI-X structures */
> -    if (bar_size & ~(MSIX_PAGE_SIZE - 1)) {
> -        return -EINVAL;
> -    }
> -
> -    config_offset = pci_add_capability(pdev, PCI_CAP_ID_MSIX,
> -                                       0, MSIX_CAP_LENGTH);
> -    if (config_offset < 0)
> -        return config_offset;
> -    config = pdev->config + config_offset;
> -
> -    pci_set_word(config + PCI_MSIX_FLAGS, nentries - 1);
> -    /* Table on top of BAR */
> -    pci_set_long(config + PCI_MSIX_TABLE, bar_size | bar_nr);
> -    /* Pending bits on top of that */
> -    pci_set_long(config + PCI_MSIX_PBA, (bar_size + MSIX_PAGE_PENDING) |
> -                 bar_nr);
> -    pdev->msix_cap = config_offset;
> -    /* Make flags bit writable. */
> -    pdev->wmask[config_offset + MSIX_CONTROL_OFFSET] |= MSIX_ENABLE_MASK |
> -	    MSIX_MASKALL_MASK;
> -    pdev->msix_function_masked = true;
> -    return 0;
> -}
> -
>  static uint8_t msix_pending_mask(int vector)
>  {
>      return 1 << (vector % 8);
> @@ -240,20 +191,6 @@ static const MemoryRegionOps msix_pba_mmio_ops = {
>      },
>  };
>  
> -static void msix_mmio_setup(PCIDevice *d, MemoryRegion *bar)
> -{
> -    uint8_t *config = d->config + d->msix_cap;
> -    uint32_t table = pci_get_long(config + PCI_MSIX_TABLE);
> -    uint32_t table_offset = table & ~PCI_MSIX_FLAGS_BIRMASK;
> -    uint32_t pba = pci_get_long(config + PCI_MSIX_PBA);
> -    uint32_t pba_offset = pba & ~PCI_MSIX_FLAGS_BIRMASK;
> -    /* TODO: for assigned devices, we'll want to make it possible to map
> -     * pending bits separately in case they are in a separate bar. */
> -
> -    memory_region_add_subregion(bar, table_offset, &d->msix_table_mmio);
> -    memory_region_add_subregion(bar, pba_offset, &d->msix_pba_mmio);
> -}
> -
>  static void msix_mask_all(struct PCIDevice *dev, unsigned nentries)
>  {
>      int vector;
> @@ -268,11 +205,72 @@ static void msix_mask_all(struct PCIDevice *dev, unsigned nentries)
>      }
>  }
>  
> -/* Initialize the MSI-X structures. Note: if MSI-X is supported, BAR size is
> - * modified, it should be retrieved with msix_bar_size. */
> +/* Add MSI-X capability to the config space for the device. */
> +static int msix_add_config(struct PCIDevice *dev, unsigned short nentries,
> +                           uint8_t table_bar, unsigned table_offset,
> +                           uint8_t pba_bar, unsigned pba_offset, uint8_t pos)

Why not fold msix_add_config into msix_init and move sanity checks to
the beginning, i.e. before resource allocations? Then you also do not
need to call msix_uninit from msix_init. Likely a matter of taste, so
not a must-have.

> +{
> +    int config_offset;
> +    uint8_t *config;
> +
> +    if (nentries < 1 || nentries > PCI_MSIX_FLAGS_QSIZE + 1) {
> +        return -EINVAL;
> +    }
> +
> +    config_offset = pci_add_capability(dev, PCI_CAP_ID_MSIX,
> +                                       pos, MSIX_CAP_LENGTH);
> +    if (config_offset < 0) {
> +        return config_offset;
> +    }
> +
> +    config = dev->config + config_offset;
> +
> +    pci_set_word(config + PCI_MSIX_FLAGS, nentries - 1);
> +    pci_set_long(config + PCI_MSIX_TABLE, table_offset | table_bar);
> +    pci_set_long(config + PCI_MSIX_PBA, pba_offset | pba_bar);
> +
> +    dev->msix_cap = config_offset;
> +
> +    /* Make flags bit writable. */
> +    dev->wmask[config_offset + MSIX_CONTROL_OFFSET] |= MSIX_ENABLE_MASK |
> +                                                       MSIX_MASKALL_MASK;
> +
> +    dev->msix_function_masked = true;
> +
> +    return 0;
> +}
> +
> +/* Clean up resources for the device. */
> +void msix_uninit(PCIDevice *dev, MemoryRegion *table_bar, MemoryRegion *pba_bar)
> +{
> +    if (!(dev->cap_present & QEMU_PCI_CAP_MSIX)) {

msix_present()

> +        return;
> +    }
> +
> +    pci_del_capability(dev, PCI_CAP_ID_MSIX, MSIX_CAP_LENGTH);
> +    dev->msix_cap = 0;
> +    dev->msix_entries_nr = 0;
> +
> +    memory_region_del_subregion(pba_bar, &dev->msix_pba_mmio);
> +    memory_region_destroy(&dev->msix_pba_mmio);
> +    g_free(dev->msix_pba);
> +    dev->msix_pba = NULL;
> +
> +    memory_region_del_subregion(table_bar, &dev->msix_table_mmio);
> +    memory_region_destroy(&dev->msix_table_mmio);
> +    g_free(dev->msix_table);
> +    dev->msix_table = NULL;
> +
> +    g_free(dev->msix_entry_used);
> +    dev->msix_entry_used = NULL;
> +    dev->cap_present &= ~QEMU_PCI_CAP_MSIX;
> +}
> +
> +/* Initialize the MSI-X structures */
>  int msix_init(struct PCIDevice *dev, unsigned short nentries,
> -              MemoryRegion *bar,
> -              unsigned bar_nr, unsigned bar_size)
> +              MemoryRegion *table_bar, uint8_t table_bar_nr,
> +              unsigned table_offset, MemoryRegion *pba_bar,
> +              uint8_t pba_bar_nr, unsigned pba_offset, uint8_t cap_pos)
>  {
>      int ret;
>      unsigned table_size, pba_size;
> @@ -281,43 +279,41 @@ int msix_init(struct PCIDevice *dev, unsigned short nentries,
>      if (!msi_supported) {
>          return -ENOTSUP;
>      }
> -    if (nentries > MSIX_MAX_ENTRIES)
> -        return -EINVAL;
>  
>      table_size = nentries * PCI_MSIX_ENTRY_SIZE;
>      pba_size = QEMU_ALIGN_UP(nentries, 64) / 8;
>  
> -    dev->msix_entry_used = g_malloc0(MSIX_MAX_ENTRIES *
> -                                        sizeof *dev->msix_entry_used);
> +    /* Sanity test: table & pba don't overlap, fit within BARs, min aligned */
> +    if ((table_bar_nr == pba_bar_nr &&
> +         ranges_overlap(table_offset, table_size, pba_offset, pba_size)) ||
> +        table_offset + table_size > memory_region_size(table_bar) ||
> +        pba_offset + pba_size > memory_region_size(pba_bar) ||
> +        (table_offset | pba_offset) & PCI_MSIX_FLAGS_BIRMASK) {
> +        return -EINVAL;
> +    }
>  
>      dev->msix_table = g_malloc0(table_size);
>      dev->msix_pba = g_malloc0(pba_size);
> +    dev->msix_entry_used = g_malloc0(nentries * sizeof *dev->msix_entry_used);
> +    dev->msix_entries_nr = nentries;
> +    dev->cap_present |= QEMU_PCI_CAP_MSIX;
> +
>      msix_mask_all(dev, nentries);
>  
>      memory_region_init_io(&dev->msix_table_mmio, &msix_table_mmio_ops, dev,
>                            "msix", table_size);
> +    memory_region_add_subregion(table_bar, table_offset, &dev->msix_table_mmio);
> +
>      memory_region_init_io(&dev->msix_pba_mmio, &msix_pba_mmio_ops, dev,
>                            "msix-pba", pba_size);
> +    memory_region_add_subregion(pba_bar, pba_offset, &dev->msix_pba_mmio);
>  
> -    dev->msix_entries_nr = nentries;
> -    ret = msix_add_config(dev, nentries, bar_nr, bar_size);
> -    if (ret)
> -        goto err_config;
> -
> -    dev->cap_present |= QEMU_PCI_CAP_MSIX;
> -    msix_mmio_setup(dev, bar);
> -    return 0;
> +    ret = msix_add_config(dev, nentries, table_bar_nr, table_offset,
> +                          pba_bar_nr, pba_offset, cap_pos);
> +    if (ret) {
> +        msix_uninit(dev, table_bar, pba_bar);
> +    }
>  
> -err_config:
> -    dev->msix_entries_nr = 0;
> -    memory_region_destroy(&dev->msix_pba_mmio);
> -    g_free(dev->msix_pba);
> -    dev->msix_pba = NULL;
> -    memory_region_destroy(&dev->msix_table_mmio);
> -    g_free(dev->msix_table);
> -    dev->msix_table = NULL;
> -    g_free(dev->msix_entry_used);
> -    dev->msix_entry_used = NULL;
>      return ret;
>  }
>  
> @@ -344,7 +340,8 @@ int msix_init_exclusive_bar(PCIDevice *dev, unsigned short nentries,
>  
>      free(name);
>  
> -    ret = msix_init(dev, nentries, &dev->msix_exclusive_bar, bar_nr, 4096);
> +    ret = msix_init(dev, nentries, &dev->msix_exclusive_bar, bar_nr, 0,
> +                    &dev->msix_exclusive_bar, bar_nr, 2048, 0);

Doesn't this have to be msix_table_mmi and msix_pba_mmio?

>      if (ret) {
>          memory_region_destroy(&dev->msix_exclusive_bar);
>          return ret;
> @@ -356,6 +353,14 @@ int msix_init_exclusive_bar(PCIDevice *dev, unsigned short nentries,
>      return 0;
>  }
>  
> +void msix_uninit_exclusive_bar(PCIDevice *dev)
> +{
> +    if (msix_present(dev)) {
> +        msix_uninit(dev, &dev->msix_exclusive_bar, &dev->msix_exclusive_bar);

Same here.

> +        memory_region_destroy(&dev->msix_exclusive_bar);
> +    }
> +}
> +
>  static void msix_free_irq_entries(PCIDevice *dev)
>  {
>      int vector;
> @@ -366,38 +371,6 @@ static void msix_free_irq_entries(PCIDevice *dev)
>      }
>  }
>  
> -/* Clean up resources for the device. */
> -int msix_uninit(PCIDevice *dev, MemoryRegion *bar)
> -{
> -    if (!msix_present(dev)) {
> -        return 0;
> -    }
> -    pci_del_capability(dev, PCI_CAP_ID_MSIX, MSIX_CAP_LENGTH);
> -    dev->msix_cap = 0;
> -    msix_free_irq_entries(dev);
> -    dev->msix_entries_nr = 0;
> -    memory_region_del_subregion(bar, &dev->msix_pba_mmio);
> -    memory_region_destroy(&dev->msix_pba_mmio);
> -    g_free(dev->msix_pba);
> -    dev->msix_pba = NULL;
> -    memory_region_del_subregion(bar, &dev->msix_table_mmio);
> -    memory_region_destroy(&dev->msix_table_mmio);
> -    g_free(dev->msix_table);
> -    dev->msix_table = NULL;
> -    g_free(dev->msix_entry_used);
> -    dev->msix_entry_used = NULL;
> -    dev->cap_present &= ~QEMU_PCI_CAP_MSIX;
> -    return 0;
> -}
> -
> -void msix_uninit_exclusive_bar(PCIDevice *dev)
> -{
> -    if (msix_present(dev)) {
> -        msix_uninit(dev, &dev->msix_exclusive_bar);
> -        memory_region_destroy(&dev->msix_exclusive_bar);
> -    }
> -}
> -
>  void msix_save(PCIDevice *dev, QEMUFile *f)
>  {
>      unsigned n = dev->msix_entries_nr;
> diff --git a/hw/msix.h b/hw/msix.h
> index bed6bfb..14b1a2e 100644
> --- a/hw/msix.h
> +++ b/hw/msix.h
> @@ -4,16 +4,18 @@
>  #include "qemu-common.h"
>  #include "pci.h"
>  
> -int msix_init(PCIDevice *pdev, unsigned short nentries,
> -              MemoryRegion *bar,
> -              unsigned bar_nr, unsigned bar_size);
> +int msix_init(PCIDevice *dev, unsigned short nentries,
> +              MemoryRegion *table_bar, uint8_t table_bar_nr,
> +              unsigned table_offset, MemoryRegion *pba_bar,
> +              uint8_t pba_bar_nr, unsigned pba_offset, uint8_t cap_pos);
>  int msix_init_exclusive_bar(PCIDevice *dev, unsigned short nentries,
>                              uint8_t bar_nr);
>  
>  void msix_write_config(PCIDevice *pci_dev, uint32_t address,
>                         uint32_t val, int len);
>  
> -int msix_uninit(PCIDevice *d, MemoryRegion *bar);
> +void msix_uninit(PCIDevice *dev, MemoryRegion *table_bar,
> +                 MemoryRegion *pba_bar);
>  void msix_uninit_exclusive_bar(PCIDevice *dev);
>  
>  unsigned int msix_nr_vectors_allocated(const PCIDevice *dev);
> 

Interfaces look good to me, the logic as well - except for the few remarks.

Jan

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