Hi, Jason,
Mostly good to me, just a few nitpicks below.
On Mon, Mar 21, 2022 at 01:54:27PM +0800, Jason Wang wrote:
> We introduce VTDBus structure as an intermediate step for searching
> the address space. This works well with SID based matching/lookup. But
> when we want to support SID plus PASID based address space lookup,
> this intermediate steps turns out to be a burden. So the patch simply
> drops the VTDBus structure and use the PCIBus and devfn as the key for
> the g_hash_table(). This simplifies the codes and the future PASID
> extension.
>
> To prevent being slower for past vtd_find_as_from_bus_num() callers, a
> vtd_as cache indexed by the bus number is introduced to store the last
> recent search result of a vtd_as belongs to a specific bus.
>
> Signed-off-by: Jason Wang <jasow...@redhat.com>
> ---
> hw/i386/intel_iommu.c | 238 +++++++++++++++++-----------------
> include/hw/i386/intel_iommu.h | 11 +-
> 2 files changed, 123 insertions(+), 126 deletions(-)
>
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 90964b201c..5851a17d0e 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -61,6 +61,16 @@
> }
> \
> }
>
> +/*
> + * PCI bus number (or SID) is not reliable since the device is usaully
> + * initalized before guest can configure the PCI bridge
> + * (SECONDARY_BUS_NUMBER).
> + */
> +struct vtd_as_key {
> + PCIBus *bus;
> + uint8_t devfn;
> +};
> +
> static void vtd_address_space_refresh_all(IntelIOMMUState *s);
> static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n);
>
> @@ -210,6 +220,31 @@ static guint vtd_uint64_hash(gconstpointer v)
> return (guint)*(const uint64_t *)v;
> }
>
> +static gboolean vtd_as_equal(gconstpointer v1, gconstpointer v2)
> +{
> + const struct vtd_as_key *key1 = v1;
> + const struct vtd_as_key *key2 = v2;
> +
> + return (key1->bus == key2->bus) && (key1->devfn == key2->devfn);
> +}
> +
> +static inline uint16_t vtd_make_source_id(uint8_t bus_num, uint8_t devfn)
> +{
> + return ((bus_num & 0xffUL) << 8) | (devfn & 0xffUL);
> +}
Nit: we could directly drop this one and use PCI_BUILD_BDF().
> +
> +/*
> + * Note that we use pointer to PCIBus as the key, so hashing/shifting
> + * based on the pointer value is intended.
Thanks for the comment; that helps.
Should we also mention that this hash is not the only interface to identify
two vtd_as*, say, even if on a 32bit system we got last 24 bits collapsed
on two vtd_as* pointers, we can still have vtd_as_equal() to guard us?
> + */
> +static guint vtd_as_hash(gconstpointer v)
> +{
> + const struct vtd_as_key *key = v;
> + guint value = (guint)(uintptr_t)key->bus;
> +
> + return (guint)(value << 8 | key->devfn);
> +}
> +
> static gboolean vtd_hash_remove_by_domain(gpointer key, gpointer value,
> gpointer user_data)
> {
> @@ -248,22 +283,14 @@ static gboolean vtd_hash_remove_by_page(gpointer key,
> gpointer value,
> static void vtd_reset_context_cache_locked(IntelIOMMUState *s)
> {
> VTDAddressSpace *vtd_as;
> - VTDBus *vtd_bus;
> - GHashTableIter bus_it;
> - uint32_t devfn_it;
> + GHashTableIter as_it;
>
> trace_vtd_context_cache_reset();
>
> - g_hash_table_iter_init(&bus_it, s->vtd_as_by_busptr);
> + g_hash_table_iter_init(&as_it, s->vtd_as);
>
> - while (g_hash_table_iter_next (&bus_it, NULL, (void**)&vtd_bus)) {
> - for (devfn_it = 0; devfn_it < PCI_DEVFN_MAX; ++devfn_it) {
> - vtd_as = vtd_bus->dev_as[devfn_it];
> - if (!vtd_as) {
> - continue;
> - }
> - vtd_as->context_cache_entry.context_cache_gen = 0;
> - }
> + while (g_hash_table_iter_next (&as_it, NULL, (void**)&vtd_as)) {
> + vtd_as->context_cache_entry.context_cache_gen = 0;
> }
> s->context_cache_gen = 1;
> }
> @@ -993,32 +1020,6 @@ static bool vtd_slpte_nonzero_rsvd(uint64_t slpte,
> uint32_t level)
> return slpte & rsvd_mask;
> }
>
> -/* Find the VTD address space associated with a given bus number */
> -static VTDBus *vtd_find_as_from_bus_num(IntelIOMMUState *s, uint8_t bus_num)
> -{
> - VTDBus *vtd_bus = s->vtd_as_by_bus_num[bus_num];
> - GHashTableIter iter;
> -
> - if (vtd_bus) {
> - return vtd_bus;
> - }
> -
> - /*
> - * Iterate over the registered buses to find the one which
> - * currently holds this bus number and update the bus_num
> - * lookup table.
> - */
> - g_hash_table_iter_init(&iter, s->vtd_as_by_busptr);
> - while (g_hash_table_iter_next(&iter, NULL, (void **)&vtd_bus)) {
> - if (pci_bus_num(vtd_bus->bus) == bus_num) {
> - s->vtd_as_by_bus_num[bus_num] = vtd_bus;
> - return vtd_bus;
> - }
> - }
> -
> - return NULL;
> -}
> -
> /* Given the @iova, get relevant @slptep. @slpte_level will be the last level
> * of the translation, can be used for deciding the size of large page.
> */
> @@ -1634,24 +1635,13 @@ static bool vtd_switch_address_space(VTDAddressSpace
> *as)
>
> static void vtd_switch_address_space_all(IntelIOMMUState *s)
> {
> + VTDAddressSpace *vtd_as;
> GHashTableIter iter;
> - VTDBus *vtd_bus;
> - int i;
> -
> - g_hash_table_iter_init(&iter, s->vtd_as_by_busptr);
> - while (g_hash_table_iter_next(&iter, NULL, (void **)&vtd_bus)) {
> - for (i = 0; i < PCI_DEVFN_MAX; i++) {
> - if (!vtd_bus->dev_as[i]) {
> - continue;
> - }
> - vtd_switch_address_space(vtd_bus->dev_as[i]);
> - }
> - }
> -}
>
> -static inline uint16_t vtd_make_source_id(uint8_t bus_num, uint8_t devfn)
> -{
> - return ((bus_num & 0xffUL) << 8) | (devfn & 0xffUL);
> + g_hash_table_iter_init(&iter, s->vtd_as);
> + while (g_hash_table_iter_next(&iter, NULL, (void **)&vtd_as)) {
> + vtd_switch_address_space(vtd_as);
> + }
> }
>
> static const bool vtd_qualified_faults[] = {
> @@ -1688,18 +1678,39 @@ static inline bool vtd_is_interrupt_addr(hwaddr addr)
> return VTD_INTERRUPT_ADDR_FIRST <= addr && addr <=
> VTD_INTERRUPT_ADDR_LAST;
> }
>
> +static gboolean vtd_find_as_by_sid(gpointer key, gpointer value,
> + gpointer user_data)
> +{
> + struct vtd_as_key *as_key = (struct vtd_as_key *)key;
> + uint16_t target_sid = *(uint16_t *)user_data;
> + uint16_t sid = vtd_make_source_id(pci_bus_num(as_key->bus),
> + as_key->devfn);
> + return sid == target_sid;
> +}
> +
> +static VTDAddressSpace *vtd_get_as_by_sid(IntelIOMMUState *s, uint16_t sid)
> +{
> + uint8_t bus_num = sid >> 8;
PCI_BUS_NUM(sid)?
> + VTDAddressSpace *vtd_as = s->vtd_as_cache[bus_num];
> +
> + if (vtd_as &&
> + (sid == vtd_make_source_id(pci_bus_num(vtd_as->bus),
> + vtd_as->devfn))) {
> + return vtd_as;
> + }
> +
> + vtd_as = g_hash_table_find(s->vtd_as, vtd_find_as_by_sid, &sid);
> + s->vtd_as_cache[bus_num] = vtd_as;
> +
> + return vtd_as;
> +}
> +
> static void vtd_pt_enable_fast_path(IntelIOMMUState *s, uint16_t source_id)
> {
> - VTDBus *vtd_bus;
> VTDAddressSpace *vtd_as;
> bool success = false;
>
> - vtd_bus = vtd_find_as_from_bus_num(s, VTD_SID_TO_BUS(source_id));
> - if (!vtd_bus) {
> - goto out;
> - }
> -
> - vtd_as = vtd_bus->dev_as[VTD_SID_TO_DEVFN(source_id)];
> + vtd_as = vtd_get_as_by_sid(s, source_id);
> if (!vtd_as) {
> goto out;
> }
> @@ -1907,11 +1918,10 @@ static void
> vtd_context_device_invalidate(IntelIOMMUState *s,
> uint16_t source_id,
> uint16_t func_mask)
> {
> + GHashTableIter as_it;
> uint16_t mask;
> - VTDBus *vtd_bus;
> VTDAddressSpace *vtd_as;
> uint8_t bus_n, devfn;
> - uint16_t devfn_it;
>
> trace_vtd_inv_desc_cc_devices(source_id, func_mask);
>
> @@ -1934,32 +1944,31 @@ static void
> vtd_context_device_invalidate(IntelIOMMUState *s,
> mask = ~mask;
>
> bus_n = VTD_SID_TO_BUS(source_id);
> - vtd_bus = vtd_find_as_from_bus_num(s, bus_n);
> - if (vtd_bus) {
> - devfn = VTD_SID_TO_DEVFN(source_id);
> - for (devfn_it = 0; devfn_it < PCI_DEVFN_MAX; ++devfn_it) {
> - vtd_as = vtd_bus->dev_as[devfn_it];
> - if (vtd_as && ((devfn_it & mask) == (devfn & mask))) {
> - trace_vtd_inv_desc_cc_device(bus_n, VTD_PCI_SLOT(devfn_it),
> - VTD_PCI_FUNC(devfn_it));
> - vtd_iommu_lock(s);
> - vtd_as->context_cache_entry.context_cache_gen = 0;
> - vtd_iommu_unlock(s);
> - /*
> - * Do switch address space when needed, in case if the
> - * device passthrough bit is switched.
> - */
> - vtd_switch_address_space(vtd_as);
> - /*
> - * So a device is moving out of (or moving into) a
> - * domain, resync the shadow page table.
> - * This won't bring bad even if we have no such
> - * notifier registered - the IOMMU notification
> - * framework will skip MAP notifications if that
> - * happened.
> - */
> - vtd_sync_shadow_page_table(vtd_as);
> - }
> + devfn = VTD_SID_TO_DEVFN(source_id);
> +
> + g_hash_table_iter_init(&as_it, s->vtd_as);
> + while (g_hash_table_iter_next(&as_it, NULL, (void**)&vtd_as)) {
> + if ((pci_bus_num(vtd_as->bus) == bus_n) &&
> + (vtd_as->devfn & mask) == (devfn & mask)) {
> + trace_vtd_inv_desc_cc_device(bus_n, VTD_PCI_SLOT(vtd_as->devfn),
> + VTD_PCI_FUNC(vtd_as->devfn));
> + vtd_iommu_lock(s);
> + vtd_as->context_cache_entry.context_cache_gen = 0;
> + vtd_iommu_unlock(s);
> + /*
> + * Do switch address space when needed, in case if the
> + * device passthrough bit is switched.
> + */
> + vtd_switch_address_space(vtd_as);
> + /*
> + * So a device is moving out of (or moving into) a
> + * domain, resync the shadow page table.
> + * This won't bring bad even if we have no such
> + * notifier registered - the IOMMU notification
> + * framework will skip MAP notifications if that
> + * happened.
> + */
> + vtd_sync_shadow_page_table(vtd_as);
> }
> }
> }
> @@ -2473,18 +2482,13 @@ static bool
> vtd_process_device_iotlb_desc(IntelIOMMUState *s,
> {
> VTDAddressSpace *vtd_dev_as;
> IOMMUTLBEvent event;
> - struct VTDBus *vtd_bus;
> hwaddr addr;
> uint64_t sz;
> uint16_t sid;
> - uint8_t devfn;
> bool size;
> - uint8_t bus_num;
>
> addr = VTD_INV_DESC_DEVICE_IOTLB_ADDR(inv_desc->hi);
> sid = VTD_INV_DESC_DEVICE_IOTLB_SID(inv_desc->lo);
> - devfn = sid & 0xff;
> - bus_num = sid >> 8;
> size = VTD_INV_DESC_DEVICE_IOTLB_SIZE(inv_desc->hi);
>
> if ((inv_desc->lo & VTD_INV_DESC_DEVICE_IOTLB_RSVD_LO) ||
> @@ -2495,12 +2499,11 @@ static bool
> vtd_process_device_iotlb_desc(IntelIOMMUState *s,
> return false;
> }
>
> - vtd_bus = vtd_find_as_from_bus_num(s, bus_num);
> - if (!vtd_bus) {
> - goto done;
> - }
> -
> - vtd_dev_as = vtd_bus->dev_as[devfn];
> + /*
> + * Using sid is OK since the guest should have finished the
> + * initialization of both the bus and device.
> + */
> + vtd_dev_as = vtd_get_as_by_sid(s, sid);
> if (!vtd_dev_as) {
> goto done;
> }
> @@ -3426,27 +3429,27 @@ static const MemoryRegionOps vtd_mem_ir_ops = {
>
> VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn)
> {
> - uintptr_t key = (uintptr_t)bus;
> - VTDBus *vtd_bus = g_hash_table_lookup(s->vtd_as_by_busptr, &key);
> + /*
> + * We can't simply use sid here since the bus number might not be
> + * initialized by the guest.
> + */
> + struct vtd_as_key key = {
> + .bus = bus,
> + .devfn = devfn,
> + };
> VTDAddressSpace *vtd_dev_as;
> char name[128];
>
> - if (!vtd_bus) {
> - uintptr_t *new_key = g_malloc(sizeof(*new_key));
> - *new_key = (uintptr_t)bus;
> - /* No corresponding free() */
> - vtd_bus = g_malloc0(sizeof(VTDBus) + sizeof(VTDAddressSpace *) * \
> - PCI_DEVFN_MAX);
> - vtd_bus->bus = bus;
> - g_hash_table_insert(s->vtd_as_by_busptr, new_key, vtd_bus);
> - }
> + vtd_dev_as = g_hash_table_lookup(s->vtd_as, &key);
> + if (!vtd_dev_as) {
> + struct vtd_as_key *new_key = g_malloc(sizeof(*new_key));
>
> - vtd_dev_as = vtd_bus->dev_as[devfn];
> + new_key->bus = bus;
> + new_key->devfn = devfn;
>
> - if (!vtd_dev_as) {
> snprintf(name, sizeof(name), "vtd-%02x.%x", PCI_SLOT(devfn),
> PCI_FUNC(devfn));
> - vtd_bus->dev_as[devfn] = vtd_dev_as =
> g_malloc0(sizeof(VTDAddressSpace));
> + vtd_dev_as = g_malloc0(sizeof(VTDAddressSpace));
>
> vtd_dev_as->bus = bus;
> vtd_dev_as->devfn = (uint8_t)devfn;
> @@ -3502,6 +3505,8 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s,
> PCIBus *bus, int devfn)
> &vtd_dev_as->nodmar, 0);
>
> vtd_switch_address_space(vtd_dev_as);
> +
> + g_hash_table_insert(s->vtd_as, new_key, vtd_dev_as);
> }
> return vtd_dev_as;
> }
> @@ -3875,7 +3880,6 @@ static void vtd_realize(DeviceState *dev, Error **errp)
>
> QLIST_INIT(&s->vtd_as_with_notifiers);
> qemu_mutex_init(&s->iommu_lock);
> - memset(s->vtd_as_by_bus_num, 0, sizeof(s->vtd_as_by_bus_num));
> memory_region_init_io(&s->csrmem, OBJECT(s), &vtd_mem_ops, s,
> "intel_iommu", DMAR_REG_SIZE);
>
> @@ -3897,8 +3901,8 @@ static void vtd_realize(DeviceState *dev, Error **errp)
> /* No corresponding destroy */
> s->iotlb = g_hash_table_new_full(vtd_uint64_hash, vtd_uint64_equal,
> g_free, g_free);
> - s->vtd_as_by_busptr = g_hash_table_new_full(vtd_uint64_hash,
> vtd_uint64_equal,
> - g_free, g_free);
> + s->vtd_as = g_hash_table_new_full(vtd_as_hash, vtd_as_equal,
> + g_free, g_free);
> vtd_init(s);
> sysbus_mmio_map(SYS_BUS_DEVICE(s), 0, Q35_HOST_BRIDGE_IOMMU_ADDR);
> pci_setup_iommu(bus, vtd_host_dma_iommu, dev);
> diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
> index 3b5ac869db..fa1bed353c 100644
> --- a/include/hw/i386/intel_iommu.h
> +++ b/include/hw/i386/intel_iommu.h
> @@ -58,7 +58,6 @@ typedef struct VTDContextEntry VTDContextEntry;
> typedef struct VTDContextCacheEntry VTDContextCacheEntry;
> typedef struct VTDAddressSpace VTDAddressSpace;
> typedef struct VTDIOTLBEntry VTDIOTLBEntry;
> -typedef struct VTDBus VTDBus;
> typedef union VTD_IR_TableEntry VTD_IR_TableEntry;
> typedef union VTD_IR_MSIAddress VTD_IR_MSIAddress;
> typedef struct VTDPASIDDirEntry VTDPASIDDirEntry;
> @@ -111,12 +110,6 @@ struct VTDAddressSpace {
> IOVATree *iova_tree; /* Traces mapped IOVA ranges */
> };
>
> -struct VTDBus {
> - PCIBus* bus; /* A reference to the bus to provide
> translation for */
> - /* A table of VTDAddressSpace objects indexed by devfn */
> - VTDAddressSpace *dev_as[];
> -};
> -
> struct VTDIOTLBEntry {
> uint64_t gfn;
> uint16_t domain_id;
> @@ -253,8 +246,8 @@ struct IntelIOMMUState {
> uint32_t context_cache_gen; /* Should be in [1,MAX] */
> GHashTable *iotlb; /* IOTLB */
>
> - GHashTable *vtd_as_by_busptr; /* VTDBus objects indexed by PCIBus*
> reference */
> - VTDBus *vtd_as_by_bus_num[VTD_PCI_BUS_MAX]; /* VTDBus objects indexed by
> bus number */
> + GHashTable *vtd_as; /* VTD address space indexed by source
> id*/
It's not indexed by source ID but vtd_as_key?
Meanwhile how about renaming it to vtd_address_spaces? Since we use vtd_as
as the name for VTDAddressSpace* in most code paths, so imho it'll be
easier to identify the two.
> + VTDAddressSpace *vtd_as_cache[VTD_PCI_BUS_MAX]; /* VTD address space
> cache */
> /* list of registered notifiers */
> QLIST_HEAD(, VTDAddressSpace) vtd_as_with_notifiers;
>
> --
> 2.25.1
>
--
Peter Xu
