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qemu/hw/vfio/trace-events
Alex Williamson 89d5202edc vfio/pci: Allow relocating MSI-X MMIO 
Recently proposed vfio-pci kernel changes (v4.16) remove the
restriction preventing userspace from mmap'ing PCI BARs in areas
overlapping the MSI-X vector table.  This change is primarily intended
to benefit host platforms which make use of system page sizes larger
than the PCI spec recommendation for alignment of MSI-X data
structures (ie. not x86_64).  In the case of POWER systems, the SPAPR
spec requires the VM to program MSI-X using hypercalls, rendering the
MSI-X vector table unused in the VM view of the device.  However,
ARM64 platforms also support 64KB pages and rely on QEMU emulation of
MSI-X.  Regardless of the kernel driver allowing mmaps overlapping
the MSI-X vector table, emulation of the MSI-X vector table also
prevents direct mapping of device MMIO spaces overlapping this page.
Thanks to the fact that PCI devices have a standard self discovery
mechanism, we can try to resolve this by relocating the MSI-X data
structures, either by creating a new PCI BAR or extending an existing
BAR and updating the MSI-X capability for the new location.  There's
even a very slim chance that this could benefit devices which do not
adhere to the PCI spec alignment guidelines on x86_64 systems.

This new x-msix-relocation option accepts the following choices:

  off: Disable MSI-X relocation, use native device config (default)
  auto: Use a known good combination for the platform/device (none yet)
  bar0..bar5: Specify the target BAR for MSI-X data structures

If compatible, the target BAR will either be created or extended and
the new portion will be used for MSI-X emulation.

The first obvious user question with this option is how to determine
whether a given platform and device might benefit from this option.
In most cases, the answer is that it won't, especially on x86_64.
Devices often dedicate an entire BAR to MSI-X and therefore no
performance sensitive registers overlap the MSI-X area.  Take for
example:

# lspci -vvvs 0a:00.0
0a:00.0 Ethernet controller: Intel Corporation I350 Gigabit Network Connection
	...
	Region 0: Memory at db680000 (32-bit, non-prefetchable) [size=512K]
	Region 3: Memory at db7f8000 (32-bit, non-prefetchable) [size=16K]
	...
	Capabilities: [70] MSI-X: Enable+ Count=10 Masked-
		Vector table: BAR=3 offset=00000000
		PBA: BAR=3 offset=00002000

This device uses the 16K bar3 for MSI-X with the vector table at
offset zero and the pending bits arrary at offset 8K, fully honoring
the PCI spec alignment guidance.  The data sheet specifically refers
to this as an MSI-X BAR.  This device would not see a benefit from
MSI-X relocation regardless of the platform, regardless of the page
size.

However, here's another example:

# lspci -vvvs 02:00.0
02:00.0 Serial Attached SCSI controller: xxxxxxxx
	...
	Region 0: I/O ports at c000 [size=256]
	Region 1: Memory at ef640000 (64-bit, non-prefetchable) [size=64K]
	Region 3: Memory at ef600000 (64-bit, non-prefetchable) [size=256K]
	...
	Capabilities: [c0] MSI-X: Enable+ Count=16 Masked-
		Vector table: BAR=1 offset=0000e000
		PBA: BAR=1 offset=0000f000

Here the MSI-X data structures are placed on separate 4K pages at the
end of a 64KB BAR.  If our host page size is 4K, we're likely fine,
but at 64KB page size, MSI-X emulation at that location prevents the
entire BAR from being directly mapped into the VM address space.
Overlapping performance sensitive registers then starts to be a very
likely scenario on such a platform.  At this point, the user could
enable tracing on vfio_region_read and vfio_region_write to determine
more conclusively if device accesses are being trapped through QEMU.

Upon finding a device and platform in need of MSI-X relocation, the
next problem is how to choose target PCI BAR to host the MSI-X data
structures.  A few key rules to keep in mind for this selection
include:

 * There are only 6 BAR slots, bar0..bar5
 * 64-bit BARs occupy two BAR slots, 'lspci -vvv' lists the first slot
 * PCI BARs are always a power of 2 in size, extending == doubling
 * The maximum size of a 32-bit BAR is 2GB
 * MSI-X data structures must reside in an MMIO BAR

Using these rules, we can evaluate each BAR of the second example
device above as follows:

 bar0: I/O port BAR, incompatible with MSI-X tables
 bar1: BAR could be extended, incurring another 64KB of MMIO
 bar2: Unavailable, bar1 is 64-bit, this register is used by bar1
 bar3: BAR could be extended, incurring another 256KB of MMIO
 bar4: Unavailable, bar3 is 64bit, this register is used by bar3
 bar5: Available, empty BAR, minimum additional MMIO

A secondary optimization we might wish to make in relocating MSI-X
is to minimize the additional MMIO required for the device, therefore
we might test the available choices in order of preference as bar5,
bar1, and finally bar3.  The original proposal for this feature
included an 'auto' option which would choose bar5 in this case, but
various drivers have been found that make assumptions about the
properties of the "first" BAR or the size of BARs such that there
appears to be no foolproof automatic selection available, requiring
known good combinations to be sourced from users.  This patch is
pre-enabled for an 'auto' selection making use of a validated lookup
table, but no entries are yet identified.

Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2018-02-06 11:08:26 -07:00

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# See docs/devel/tracing.txt for syntax documentation.
# hw/vfio/pci.c
vfio_intx_interrupt(const char *name, char line) " (%s) Pin %c"
vfio_intx_eoi(const char *name) " (%s) EOI"
vfio_intx_enable_kvm(const char *name) " (%s) KVM INTx accel enabled"
vfio_intx_disable_kvm(const char *name) " (%s) KVM INTx accel disabled"
vfio_intx_update(const char *name, int new_irq, int target_irq) " (%s) IRQ moved %d -> %d"
vfio_intx_enable(const char *name) " (%s)"
vfio_intx_disable(const char *name) " (%s)"
vfio_msi_interrupt(const char *name, int index, uint64_t addr, int data) " (%s) vector %d 0x%"PRIx64"/0x%x"
vfio_msix_vector_do_use(const char *name, int index) " (%s) vector %d used"
vfio_msix_vector_release(const char *name, int index) " (%s) vector %d released"
vfio_msix_enable(const char *name) " (%s)"
vfio_msix_pba_disable(const char *name) " (%s)"
vfio_msix_pba_enable(const char *name) " (%s)"
vfio_msix_disable(const char *name) " (%s)"
vfio_msix_fixup(const char *name, int bar, uint64_t start, uint64_t end) " (%s) MSI-X region %d mmap fixup [0x%"PRIx64" - 0x%"PRIx64"]"
vfio_msix_relo_cost(const char *name, int bar, uint64_t cost) " (%s) BAR %d cost 0x%"PRIx64""
vfio_msix_relo(const char *name, int bar, uint64_t offset) " (%s) BAR %d offset 0x%"PRIx64""
vfio_msi_enable(const char *name, int nr_vectors) " (%s) Enabled %d MSI vectors"
vfio_msi_disable(const char *name) " (%s)"
vfio_pci_load_rom(const char *name, unsigned long size, unsigned long offset, unsigned long flags) "Device %s ROM:\n size: 0x%lx, offset: 0x%lx, flags: 0x%lx"
vfio_rom_read(const char *name, uint64_t addr, int size, uint64_t data) " (%s, 0x%"PRIx64", 0x%x) = 0x%"PRIx64
vfio_pci_size_rom(const char *name, int size) "%s ROM size 0x%x"
vfio_vga_write(uint64_t addr, uint64_t data, int size) " (0x%"PRIx64", 0x%"PRIx64", %d)"
vfio_vga_read(uint64_t addr, int size, uint64_t data) " (0x%"PRIx64", %d) = 0x%"PRIx64
vfio_pci_read_config(const char *name, int addr, int len, int val) " (%s, @0x%x, len=0x%x) 0x%x"
vfio_pci_write_config(const char *name, int addr, int val, int len) " (%s, @0x%x, 0x%x, len=0x%x)"
vfio_msi_setup(const char *name, int pos) "%s PCI MSI CAP @0x%x"
vfio_msix_early_setup(const char *name, int pos, int table_bar, int offset, int entries) "%s PCI MSI-X CAP @0x%x, BAR %d, offset 0x%x, entries %d"
vfio_check_pcie_flr(const char *name) "%s Supports FLR via PCIe cap"
vfio_check_pm_reset(const char *name) "%s Supports PM reset"
vfio_check_af_flr(const char *name) "%s Supports FLR via AF cap"
vfio_pci_hot_reset(const char *name, const char *type) " (%s) %s"
vfio_pci_hot_reset_has_dep_devices(const char *name) "%s: hot reset dependent devices:"
vfio_pci_hot_reset_dep_devices(int domain, int bus, int slot, int function, int group_id) "\t%04x:%02x:%02x.%x group %d"
vfio_pci_hot_reset_result(const char *name, const char *result) "%s hot reset: %s"
vfio_populate_device_config(const char *name, unsigned long size, unsigned long offset, unsigned long flags) "Device %s config:\n size: 0x%lx, offset: 0x%lx, flags: 0x%lx"
vfio_populate_device_get_irq_info_failure(void) "VFIO_DEVICE_GET_IRQ_INFO failure: %m"
vfio_realize(const char *name, int group_id) " (%s) group %d"
vfio_add_ext_cap_dropped(const char *name, uint16_t cap, uint16_t offset) "%s 0x%x@0x%x"
vfio_pci_reset(const char *name) " (%s)"
vfio_pci_reset_flr(const char *name) "%s FLR/VFIO_DEVICE_RESET"
vfio_pci_reset_pm(const char *name) "%s PCI PM Reset"
vfio_pci_emulated_vendor_id(const char *name, uint16_t val) "%s 0x%04x"
vfio_pci_emulated_device_id(const char *name, uint16_t val) "%s 0x%04x"
vfio_pci_emulated_sub_vendor_id(const char *name, uint16_t val) "%s 0x%04x"
vfio_pci_emulated_sub_device_id(const char *name, uint16_t val) "%s 0x%04x"
# hw/vfio/pci-quirks.c
vfio_quirk_rom_blacklisted(const char *name, uint16_t vid, uint16_t did) "%s %04x:%04x"
vfio_quirk_generic_window_address_write(const char *name, const char * region_name, uint64_t data) "%s %s 0x%"PRIx64
vfio_quirk_generic_window_data_read(const char *name, const char * region_name, uint64_t data) "%s %s 0x%"PRIx64
vfio_quirk_generic_window_data_write(const char *name, const char * region_name, uint64_t data) "%s %s 0x%"PRIx64
vfio_quirk_generic_mirror_read(const char *name, const char * region_name, uint64_t addr, uint64_t data) "%s %s 0x%"PRIx64": 0x%"PRIx64
vfio_quirk_generic_mirror_write(const char *name, const char * region_name, uint64_t addr, uint64_t data) "%s %s 0x%"PRIx64": 0x%"PRIx64
vfio_quirk_ati_3c3_read(const char *name, uint64_t data) "%s 0x%"PRIx64
vfio_quirk_ati_3c3_probe(const char *name) "%s"
vfio_quirk_ati_bar4_probe(const char *name) "%s"
vfio_quirk_ati_bar2_probe(const char *name) "%s"
vfio_quirk_nvidia_3d0_state(const char *name, const char *state) "%s %s"
vfio_quirk_nvidia_3d0_read(const char *name, uint8_t offset, unsigned size, uint64_t val) " (%s, @0x%x, len=0x%x) 0x%"PRIx64
vfio_quirk_nvidia_3d0_write(const char *name, uint8_t offset, uint64_t data, unsigned size) "(%s, @0x%x, 0x%"PRIx64", len=0x%x)"
vfio_quirk_nvidia_3d0_probe(const char *name) "%s"
vfio_quirk_nvidia_bar5_state(const char *name, const char *state) "%s %s"
vfio_quirk_nvidia_bar5_probe(const char *name) "%s"
vfio_quirk_nvidia_bar0_msi_ack(const char *name) "%s"
vfio_quirk_nvidia_bar0_probe(const char *name) "%s"
vfio_quirk_rtl8168_fake_latch(const char *name, uint64_t val) "%s 0x%"PRIx64
vfio_quirk_rtl8168_msix_write(const char *name, uint16_t offset, uint64_t val) "%s MSI-X table write[0x%x]: 0x%"PRIx64
vfio_quirk_rtl8168_msix_read(const char *name, uint16_t offset, uint64_t val) "%s MSI-X table read[0x%x]: 0x%"PRIx64
vfio_quirk_rtl8168_probe(const char *name) "%s"
vfio_quirk_ati_bonaire_reset_skipped(const char *name) "%s"
vfio_quirk_ati_bonaire_reset_no_smc(const char *name) "%s"
vfio_quirk_ati_bonaire_reset_timeout(const char *name) "%s"
vfio_quirk_ati_bonaire_reset_done(const char *name) "%s"
vfio_quirk_ati_bonaire_reset(const char *name) "%s"
vfio_pci_igd_bar4_write(const char *name, uint32_t index, uint32_t data, uint32_t base) "%s [0x%03x] 0x%08x -> 0x%08x"
vfio_pci_igd_bdsm_enabled(const char *name, int size) "%s %dMB"
vfio_pci_igd_opregion_enabled(const char *name) "%s"
vfio_pci_igd_host_bridge_enabled(const char *name) "%s"
vfio_pci_igd_lpc_bridge_enabled(const char *name) "%s"
# hw/vfio/common.c
vfio_region_write(const char *name, int index, uint64_t addr, uint64_t data, unsigned size) " (%s:region%d+0x%"PRIx64", 0x%"PRIx64 ", %d)"
vfio_region_read(char *name, int index, uint64_t addr, unsigned size, uint64_t data) " (%s:region%d+0x%"PRIx64", %d) = 0x%"PRIx64
vfio_iommu_map_notify(const char *op, uint64_t iova_start, uint64_t iova_end) "iommu %s @ 0x%"PRIx64" - 0x%"PRIx64
vfio_listener_region_add_skip(uint64_t start, uint64_t end) "SKIPPING region_add 0x%"PRIx64" - 0x%"PRIx64
vfio_listener_region_add_iommu(uint64_t start, uint64_t end) "region_add [iommu] 0x%"PRIx64" - 0x%"PRIx64
vfio_listener_region_add_ram(uint64_t iova_start, uint64_t iova_end, void *vaddr) "region_add [ram] 0x%"PRIx64" - 0x%"PRIx64" [%p]"
vfio_listener_region_del_skip(uint64_t start, uint64_t end) "SKIPPING region_del 0x%"PRIx64" - 0x%"PRIx64
vfio_listener_region_del(uint64_t start, uint64_t end) "region_del 0x%"PRIx64" - 0x%"PRIx64
vfio_disconnect_container(int fd) "close container->fd=%d"
vfio_put_group(int fd) "close group->fd=%d"
vfio_get_device(const char * name, unsigned int flags, unsigned int num_regions, unsigned int num_irqs) "Device %s flags: %u, regions: %u, irqs: %u"
vfio_put_base_device(int fd) "close vdev->fd=%d"
vfio_region_setup(const char *dev, int index, const char *name, unsigned long flags, unsigned long offset, unsigned long size) "Device %s, region %d \"%s\", flags: 0x%lx, offset: 0x%lx, size: 0x%lx"
vfio_region_mmap_fault(const char *name, int index, unsigned long offset, unsigned long size, int fault) "Region %s mmaps[%d], [0x%lx - 0x%lx], fault: %d"
vfio_region_mmap(const char *name, unsigned long offset, unsigned long end) "Region %s [0x%lx - 0x%lx]"
vfio_region_exit(const char *name, int index) "Device %s, region %d"
vfio_region_finalize(const char *name, int index) "Device %s, region %d"
vfio_region_mmaps_set_enabled(const char *name, bool enabled) "Region %s mmaps enabled: %d"
vfio_region_sparse_mmap_header(const char *name, int index, int nr_areas) "Device %s region %d: %d sparse mmap entries"
vfio_region_sparse_mmap_entry(int i, unsigned long start, unsigned long end) "sparse entry %d [0x%lx - 0x%lx]"
vfio_get_dev_region(const char *name, int index, uint32_t type, uint32_t subtype) "%s index %d, %08x/%0x8"
# hw/vfio/platform.c
vfio_platform_base_device_init(char *name, int groupid) "%s belongs to group #%d"
vfio_platform_realize(char *name, char *compat) "vfio device %s, compat = %s"
vfio_platform_eoi(int pin, int fd) "EOI IRQ pin %d (fd=%d)"
vfio_platform_intp_mmap_enable(int pin) "IRQ #%d still active, stay in slow path"
vfio_platform_intp_interrupt(int pin, int fd) "Inject IRQ #%d (fd = %d)"
vfio_platform_intp_inject_pending_lockheld(int pin, int fd) "Inject pending IRQ #%d (fd = %d)"
vfio_platform_populate_interrupts(int pin, int count, int flags) "- IRQ index %d: count %d, flags=0x%x"
vfio_intp_interrupt_set_pending(int index) "irq %d is set PENDING"
vfio_platform_start_level_irqfd_injection(int index, int fd, int resamplefd) "IRQ index=%d, fd = %d, resamplefd = %d"
vfio_platform_start_edge_irqfd_injection(int index, int fd) "IRQ index=%d, fd = %d"
# hw/vfio/spapr.c
vfio_prereg_listener_region_add_skip(uint64_t start, uint64_t end) "0x%"PRIx64" - 0x%"PRIx64
vfio_prereg_listener_region_del_skip(uint64_t start, uint64_t end) "0x%"PRIx64" - 0x%"PRIx64
vfio_prereg_register(uint64_t va, uint64_t size, int ret) "va=0x%"PRIx64" size=0x%"PRIx64" ret=%d"
vfio_prereg_unregister(uint64_t va, uint64_t size, int ret) "va=0x%"PRIx64" size=0x%"PRIx64" ret=%d"
vfio_spapr_create_window(int ps, uint64_t ws, uint64_t off) "pageshift=0x%x winsize=0x%"PRIx64" offset=0x%"PRIx64
vfio_spapr_remove_window(uint64_t off) "offset=0x%"PRIx64
vfio_spapr_group_attach(int groupfd, int tablefd) "Attached groupfd %d to liobn fd %d"
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