On 7/16/25 09:31, Sairaj Kodilkar wrote:
> The AMD IOMMU is set up at boot time and uses PCI bus numbers + devfn
> for indexing into DTE. The problem is that before the guest started,
> all PCI bus numbers are 0 as no PCI discovery happened yet (BIOS or/and
> kernel will do that later) so relying on the bus number is wrong.
> The immediate effect is emulated devices cannot do DMA when places on
> a bus other that 0.
>
> Replace static array of address_space with hash table which uses devfn and
> PCIBus* for key as it is not going to change after the guest is booted.
>
> Co-developed-by: Alexey Kardashevskiy <a...@amd.com>
> Signed-off-by: Alexey Kardashevskiy <a...@amd.com>
> Signed-off-by: Sairaj Kodilkar <sarun...@amd.com>
> ---
> hw/i386/amd_iommu.c | 124 +++++++++++++++++++++++++++-----------------
> hw/i386/amd_iommu.h | 2 +-
> 2 files changed, 76 insertions(+), 50 deletions(-)
>
> diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
> index a34062153194..33916b458611 100644
> --- a/hw/i386/amd_iommu.c
> +++ b/hw/i386/amd_iommu.c
> @@ -59,7 +59,7 @@ const char *amdvi_mmio_high[] = {
> };
>
> struct AMDVIAddressSpace {
> - uint8_t bus_num; /* bus number */
> + PCIBus *bus; /* PCIBus (for bus number) */
> uint8_t devfn; /* device function */
> AMDVIState *iommu_state; /* AMDVI - one per machine */
> MemoryRegion root; /* AMDVI Root memory map region */
> @@ -101,6 +101,11 @@ typedef enum AMDVIFaultReason {
> AMDVI_FR_PT_ENTRY_INV, /* Failure to read PTE from guest memory */
> } AMDVIFaultReason;
>
> +typedef struct amdvi_as_key {
> + PCIBus *bus;
> + int devfn;
> +} amdvi_as_key;
> +
> uint64_t amdvi_extended_feature_register(AMDVIState *s)
> {
> uint64_t feature = AMDVI_DEFAULT_EXT_FEATURES;
> @@ -360,6 +365,42 @@ static guint amdvi_uint64_hash(gconstpointer v)
> return (guint)*(const uint64_t *)v;
> }
>
> +static gboolean amdvi_as_equal(gconstpointer v1, gconstpointer v2)
> +{
> + const struct amdvi_as_key *key1 = v1;
> + const struct amdvi_as_key *key2 = v2;
> +
> + return key1->bus == key2->bus && key1->devfn == key2->devfn;
> +}
> +
> +static guint amdvi_as_hash(gconstpointer v)
> +{
> + const struct amdvi_as_key *key = v;
> + return (guint)((uint64_t)key->bus | (key->devfn << 24));
I think it should at least be a xor, but a hash similar to the
intel one is probably preferable:
return (guint)((uintptr_t)key->bus << 8) | key->devfn);
> +}
> +
> +static AMDVIAddressSpace *amdvi_as_lookup(AMDVIState *s, PCIBus *bus,
> + int devfn)
> +{
> + amdvi_as_key key = { .bus = bus, .devfn = devfn };
> + return g_hash_table_lookup(s->address_spaces, &key);
> +}
> +
> +static int amdvi_find_as_by_devid(gpointer key, gpointer value,
> + gpointer user_data)
> +{
> + amdvi_as_key *as = (struct amdvi_as_key *)key;
> + uint16_t devid = *((uint16_t *)user_data);
> +
> + return devid == PCI_BUILD_BDF(pci_bus_num(as->bus), as->devfn);
> +}
> +
> +static AMDVIAddressSpace *amdvi_get_as_by_devid(AMDVIState *s, uint16_t
> devid)
> +{
> + return g_hash_table_find(s->address_spaces,
> + amdvi_find_as_by_devid, &devid);
> +}
> +
> static AMDVIIOTLBEntry *amdvi_iotlb_lookup(AMDVIState *s, hwaddr addr,
> uint64_t devid)
> {
> @@ -530,7 +571,7 @@ static inline uint64_t amdvi_get_pte_entry(AMDVIState *s,
> uint64_t pte_addr,
>
> static int amdvi_as_to_dte(AMDVIAddressSpace *as, uint64_t *dte)
> {
> - uint16_t devid = PCI_BUILD_BDF(as->bus_num, as->devfn);
> + uint16_t devid = PCI_BUILD_BDF(pci_bus_num(as->bus), as->devfn);
> AMDVIState *s = as->iommu_state;
>
> if (!amdvi_get_dte(s, devid, dte)) {
> @@ -983,23 +1024,13 @@ static void
> amdvi_switch_address_space(AMDVIAddressSpace *amdvi_as)
> */
> static void amdvi_switch_address_space_all(AMDVIState *s)
> {
> - AMDVIAddressSpace **iommu_as;
> -
> - for (int bus_num = 0; bus_num < PCI_BUS_MAX; bus_num++) {
> -
> - /* Nothing to do if there are no devices on the current bus */
> - if (!s->address_spaces[bus_num]) {
> - continue;
> - }
> - iommu_as = s->address_spaces[bus_num];
> + AMDVIAddressSpace *iommu_as;
> + GHashTableIter as_it;
>
> - for (int devfn = 0; devfn < PCI_DEVFN_MAX; devfn++) {
> + g_hash_table_iter_init(&as_it, s->address_spaces);
>
> - if (!iommu_as[devfn]) {
> - continue;
> - }
> - amdvi_switch_address_space(iommu_as[devfn]);
> - }
> + while (g_hash_table_iter_next(&as_it, NULL, (void **)&iommu_as)) {
> + amdvi_switch_address_space(iommu_as);
> }
> }
>
> @@ -1012,28 +1043,22 @@ static void amdvi_switch_address_space_all(AMDVIState
> *s)
> */
> static void amdvi_update_addr_translation_mode(AMDVIState *s, uint16_t devid)
> {
> - uint8_t bus_num, devfn, dte_mode;
> + uint8_t dte_mode;
> AMDVIAddressSpace *as;
> uint64_t dte[4] = { 0 };
> IOMMUNotifier *n;
> int ret;
>
> - /*
> - * Convert the devid encoded in the command to a bus and devfn in
> - * order to retrieve the corresponding address space.
> - */
> - bus_num = PCI_BUS_NUM(devid);
> - devfn = devid & 0xff;
> -
> /*
> * The main buffer of size (AMDVIAddressSpace *) * (PCI_BUS_MAX) has
> already
> * been allocated within AMDVIState, but must be careful to not access
> * unallocated devfn.
> */
> - if (!s->address_spaces[bus_num] || !s->address_spaces[bus_num][devfn]) {
> +
> + as = amdvi_get_as_by_devid(s, devid);
> + if (!as) {
> return;
> }
> - as = s->address_spaces[bus_num][devfn];
>
> ret = amdvi_as_to_dte(as, dte);
>
> @@ -1699,7 +1724,7 @@ static void amdvi_do_translate(AMDVIAddressSpace *as,
> hwaddr addr,
> bool is_write, IOMMUTLBEntry *ret)
> {
> AMDVIState *s = as->iommu_state;
> - uint16_t devid = PCI_BUILD_BDF(as->bus_num, as->devfn);
> + uint16_t devid = PCI_BUILD_BDF(pci_bus_num(as->bus), as->devfn);
> AMDVIIOTLBEntry *iotlb_entry = amdvi_iotlb_lookup(s, addr, devid);
> uint64_t entry[4];
> int dte_ret;
> @@ -1773,7 +1798,7 @@ static IOMMUTLBEntry amdvi_translate(IOMMUMemoryRegion
> *iommu, hwaddr addr,
> }
>
> amdvi_do_translate(as, addr, flag & IOMMU_WO, &ret);
> - trace_amdvi_translation_result(as->bus_num, PCI_SLOT(as->devfn),
> + trace_amdvi_translation_result(pci_bus_num(as->bus), PCI_SLOT(as->devfn),
> PCI_FUNC(as->devfn), addr, ret.translated_addr);
> return ret;
> }
> @@ -2137,30 +2162,28 @@ static AddressSpace *amdvi_host_dma_iommu(PCIBus
> *bus, void *opaque, int devfn)
> {
> char name[128];
> AMDVIState *s = opaque;
> - AMDVIAddressSpace **iommu_as, *amdvi_dev_as;
> - int bus_num = pci_bus_num(bus);
> + AMDVIAddressSpace *amdvi_dev_as;
> + amdvi_as_key *key;
>
> - iommu_as = s->address_spaces[bus_num];
> + amdvi_dev_as = amdvi_as_lookup(s, bus, devfn);
>
> /* allocate memory during the first run */
> - if (!iommu_as) {
> - iommu_as = g_new0(AMDVIAddressSpace *, PCI_DEVFN_MAX);
> - s->address_spaces[bus_num] = iommu_as;
> - }
> -
> - /* set up AMD-Vi region */
> - if (!iommu_as[devfn]) {
> + if (!amdvi_dev_as) {
> snprintf(name, sizeof(name), "amd_iommu_devfn_%d", devfn);
>
> - iommu_as[devfn] = g_new0(AMDVIAddressSpace, 1);
> - iommu_as[devfn]->bus_num = (uint8_t)bus_num;
> - iommu_as[devfn]->devfn = (uint8_t)devfn;
> - iommu_as[devfn]->iommu_state = s;
> - iommu_as[devfn]->notifier_flags = IOMMU_NONE;
s/IOMMU_NONE/IOMMU_NOTIFIER_NONE
Thanks,
Ethan
> - iommu_as[devfn]->iova_tree = iova_tree_new();
> - iommu_as[devfn]->addr_translation = false;
> + amdvi_dev_as = g_new0(AMDVIAddressSpace, 1);
> + key = g_new0(amdvi_as_key, 1);
>
> - amdvi_dev_as = iommu_as[devfn];
> + amdvi_dev_as->bus = bus;
> + amdvi_dev_as->devfn = (uint8_t)devfn;
> + amdvi_dev_as->iommu_state = s;
> + amdvi_dev_as->notifier_flags = IOMMU_NONE;
> + amdvi_dev_as->iova_tree = iova_tree_new();
> + amdvi_dev_as->addr_translation = false;
> + key->bus = bus;
> + key->devfn = devfn;
> +
> + g_hash_table_insert(s->address_spaces, key, amdvi_dev_as);
>
> /*
> * Memory region relationships looks like (Address range shows
> @@ -2203,7 +2226,7 @@ static AddressSpace *amdvi_host_dma_iommu(PCIBus *bus,
> void *opaque, int devfn)
>
> amdvi_switch_address_space(amdvi_dev_as);
> }
> - return &iommu_as[devfn]->as;
> + return &amdvi_dev_as->as;
> }
>
> static const PCIIOMMUOps amdvi_iommu_ops = {
> @@ -2244,7 +2267,7 @@ static int
> amdvi_iommu_notify_flag_changed(IOMMUMemoryRegion *iommu,
> if (!s->dma_remap && (new & IOMMU_NOTIFIER_MAP)) {
> error_setg_errno(errp, ENOTSUP,
> "device %02x.%02x.%x requires dma-remap=1",
> - as->bus_num, PCI_SLOT(as->devfn), PCI_FUNC(as->devfn));
> + pci_bus_num(as->bus), PCI_SLOT(as->devfn),
> PCI_FUNC(as->devfn));
> return -ENOTSUP;
> }
>
> @@ -2353,6 +2376,9 @@ static void amdvi_sysbus_realize(DeviceState *dev,
> Error **errp)
> s->iotlb = g_hash_table_new_full(amdvi_uint64_hash,
> amdvi_uint64_equal, g_free, g_free);
>
> + s->address_spaces = g_hash_table_new_full(amdvi_as_hash,
> + amdvi_as_equal, g_free, g_free);
> +
> /* This device should take care of IOMMU PCI properties */
> if (!qdev_realize(DEVICE(&s->pci), &bus->qbus, errp)) {
> return;
> diff --git a/hw/i386/amd_iommu.h b/hw/i386/amd_iommu.h
> index 3dd4e7e3e8b8..37a57c4dd553 100644
> --- a/hw/i386/amd_iommu.h
> +++ b/hw/i386/amd_iommu.h
> @@ -409,7 +409,7 @@ struct AMDVIState {
> bool mmio_enabled;
>
> /* for each served device */
> - AMDVIAddressSpace **address_spaces[PCI_BUS_MAX];
> + GHashTable *address_spaces;
>
> /* list of address spaces with registered notifiers */
> QLIST_HEAD(, AMDVIAddressSpace) amdvi_as_with_notifiers;
> --
> 2.34.1
>
>
