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Re: [PATCH V2 2/4] intel-iommu: drop VTDBus
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From: |
Jason Wang |
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Subject: |
Re: [PATCH V2 2/4] intel-iommu: drop VTDBus |
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Date: |
Fri, 22 Apr 2022 14:26:11 +0800 |
On Fri, Apr 22, 2022 at 9:17 AM Peter Xu <peterx@redhat.com> wrote:
>
> 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 <jasowang@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().
Will fix.
>
> > +
> > +/*
> > + * 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?
Ok. let me add that in the next version.
>
> > + */
> > +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)?
Will do.
>
> > + 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?
Right, let me fix that.
>
> 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.
Ok.
Thanks
>
> > + 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
>