Latest Intel platform Granite Rapids has introduced a new instruction -
PREFETCHIT0/1, which moves code to memory (cache) closer to the
processor depending on specific hints.
The bit definition:
CPUID.(EAX=7,ECX=1):EDX[bit 14]
Add CPUID definition for PREFETCHIT0/1.
Signed-off-by: Jiaxi Chen <jiaxi.chen@linux.intel.com>
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20230303065913.1246327-7-tao1.su@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
AVX-NE-CONVERT is a new set of instructions which can convert low
precision floating point like BF16/FP16 to high precision floating point
FP32, as well as convert FP32 elements to BF16. This instruction allows
the platform to have improved AI capabilities and better compatibility.
The bit definition:
CPUID.(EAX=7,ECX=1):EDX[bit 5]
Add CPUID definition for AVX-NE-CONVERT.
Signed-off-by: Jiaxi Chen <jiaxi.chen@linux.intel.com>
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20230303065913.1246327-6-tao1.su@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
AVX-VNNI-INT8 is a new set of instructions in the latest Intel platform
Sierra Forest, aims for the platform to have superior AI capabilities.
This instruction multiplies the individual bytes of two unsigned or
unsigned source operands, then adds and accumulates the results into the
destination dword element size operand.
The bit definition:
CPUID.(EAX=7,ECX=1):EDX[bit 4]
AVX-VNNI-INT8 is on a new feature bits leaf. Add a CPUID feature word
FEAT_7_1_EDX for this leaf.
Add CPUID definition for AVX-VNNI-INT8.
Signed-off-by: Jiaxi Chen <jiaxi.chen@linux.intel.com>
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20230303065913.1246327-5-tao1.su@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
AVX-IFMA is a new instruction in the latest Intel platform Sierra
Forest. This instruction packed multiplies unsigned 52-bit integers and
adds the low/high 52-bit products to Qword Accumulators.
The bit definition:
CPUID.(EAX=7,ECX=1):EAX[bit 23]
Add CPUID definition for AVX-IFMA.
Signed-off-by: Jiaxi Chen <jiaxi.chen@linux.intel.com>
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20230303065913.1246327-4-tao1.su@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Latest Intel platform Granite Rapids has introduced a new instruction -
AMX-FP16, which performs dot-products of two FP16 tiles and accumulates
the results into a packed single precision tile. AMX-FP16 adds FP16
capability and allows a FP16 GPU trained model to run faster without
loss of accuracy or added SW overhead.
The bit definition:
CPUID.(EAX=7,ECX=1):EAX[bit 21]
Add CPUID definition for AMX-FP16.
Signed-off-by: Jiaxi Chen <jiaxi.chen@linux.intel.com>
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20230303065913.1246327-3-tao1.su@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
CMPccXADD is a new set of instructions in the latest Intel platform
Sierra Forest. This new instruction set includes a semaphore operation
that can compare and add the operands if condition is met, which can
improve database performance.
The bit definition:
CPUID.(EAX=7,ECX=1):EAX[bit 7]
Add CPUID definition for CMPCCXADD.
Signed-off-by: Jiaxi Chen <jiaxi.chen@linux.intel.com>
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20230303065913.1246327-2-tao1.su@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Update the setting of CPUID 0x8000001F EBX to clearly document the ranges
associated with fields being set.
Fixes: 6cb8f2a663 ("cpu/i386: populate CPUID 0x8000_001F when SEV is active")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <5822fd7d02b575121380e1f493a8f6d9eba2b11a.1664550870.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The value of the reduced-phys-bits parameter is propogated to the CPUID
information exposed to the guest. Update the current validation check to
account for the size of the CPUID field (6-bits), ensuring the value is
in the range of 1 to 63.
Maintain backward compatibility, to an extent, by allowing a value greater
than 1 (so that the previously documented value of 5 still works), but not
allowing anything over 63.
Fixes: d8575c6c02 ("sev/i386: add command to initialize the memory encryption context")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <cca5341a95ac73f904e6300f10b04f9c62e4e8ff.1664550870.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We want to get rid of the "#ifdef TARGET_X86_64" compile-time switch
in the long run, so we can drop the separate compilation of the
"qemu-system-i386" binary one day - but we then still need a way to
run a guest with max. CPU settings in 32-bit mode. So the "max" CPU
should determine its family/model/stepping settings according to the
"large mode" (LM) CPU feature bit during runtime, so that it is
possible to run "qemu-system-x86_64 -cpu max,lm=off" and still get
a sane family/model/stepping setting for the guest CPU.
To be able to check the LM bit, we have to move the code that sets
up these properties to a "realize" function, since the LM setting is
not available yet when the "instance_init" function is being called.
Message-Id: <20230306154311.476458-1-thuth@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
The previous patch wrongly replaced FEAT_XSAVE_XCR0_{LO|HI} with
FEAT_XSAVE_XSS_{LO|HI} in CPUID(EAX=12,ECX=1):{ECX,EDX}. As a result,
SGX enclaves only supported SSE and x87 feature (xfrm=0x3).
Fixes: 301e90675c ("target/i386: Enable support for XSAVES based features")
Signed-off-by: Yang Zhong <yang.zhong@linux.intel.com>
Reviewed-by: Yang Weijiang <weijiang.yang@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Message-Id: <20230406064041.420039-1-yang.zhong@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Coverity complains (CID 1507880) that the declaration "int error_code;"
in mmu_translate() is unreachable code. Since this is only a declaration,
this isn't actually a bug, but:
* it's a bear-trap for future changes, because if it was changed to
include an initialization 'int error_code = foo;' then the
initialization wouldn't actually happen (being dead code)
* it's against our coding style, which wants declarations to be
at the start of blocks
* it means that anybody reading the code has to go and look up
exactly what the C rules are for skipping over variable declarations
using a goto
Move the declaration to the top of the function.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20230406155946.3362077-1-peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This had been pulled in via qemu/plugin.h from hw/core/cpu.h,
but that will be removed.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230310195252.210956-5-richard.henderson@linaro.org>
[AJB: add various additional cases shown by CI]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230315174331.2959-15-alex.bennee@linaro.org>
Reviewed-by: Emilio Cota <cota@braap.org>
Upstream commit ddf0fd9ae1 "hw/xen: Support HVM_PARAM_CALLBACK_TYPE_GSI callback"
added kvm_xen_maybe_deassert_callback usage to target/i386/kvm/kvm.c file without
conditional preprocessing check. This breaks any build not using CONFIG_XEN_EMU.
Protect call by conditional preprocessing to allow build without CONFIG_XEN_EMU.
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20230308130557.2420-1-mrezanin@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
All uses are strictly read-only. Most of the obviously so,
as direct arguments to gen_helper_*.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230306175230.7110-9-anjo@rev.ng>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
- split user and softmmu code
- use cleaner headers for tb_flush, target_ulong
- probe for gdb multiarch support at configure
- make syscall handling target independent
- add update guest debug of accel ops
-----BEGIN PGP SIGNATURE-----
iQEzBAABCgAdFiEEZoWumedRZ7yvyN81+9DbCVqeKkQFAmQHomMACgkQ+9DbCVqe
KkTtFAf/aEyKY0iUNxtB4/oV1L2VnLaZi+iKoZT4RQgrhOhzr5WV6/3/V05cw1RJ
SIwcl8wB4gowYILs44eM/Qzcixiugl++2rvM4YVXiQyWKzkH6sY4X2iFuPGTwHLp
y+E7RM77QNS7M9xYaVkdsQawnbsgjG67wZKbb88aaekFEn61UuDg1V2Nqa2ICy7Y
/8yGIB2ixDfXOF0z4g8NOG44BXTDBtJbcEzf5GMz6D4HGnPZUbENy1nT0OcBk3zK
PqKPNkPFZ360pqA9MtougjZ3xTBb7Afe9nRRMquV2RoFmkkY2otSjdPBFQu5GBlm
NyTXEzjIQ6tCZlbS0eqdPVrUHHUx9g==
=Al36
-----END PGP SIGNATURE-----
Merge tag 'pull-gdbstub-070323-3' of https://gitlab.com/stsquad/qemu into staging
gdbstub refactor:
- split user and softmmu code
- use cleaner headers for tb_flush, target_ulong
- probe for gdb multiarch support at configure
- make syscall handling target independent
- add update guest debug of accel ops
# -----BEGIN PGP SIGNATURE-----
#
# iQEzBAABCgAdFiEEZoWumedRZ7yvyN81+9DbCVqeKkQFAmQHomMACgkQ+9DbCVqe
# KkTtFAf/aEyKY0iUNxtB4/oV1L2VnLaZi+iKoZT4RQgrhOhzr5WV6/3/V05cw1RJ
# SIwcl8wB4gowYILs44eM/Qzcixiugl++2rvM4YVXiQyWKzkH6sY4X2iFuPGTwHLp
# y+E7RM77QNS7M9xYaVkdsQawnbsgjG67wZKbb88aaekFEn61UuDg1V2Nqa2ICy7Y
# /8yGIB2ixDfXOF0z4g8NOG44BXTDBtJbcEzf5GMz6D4HGnPZUbENy1nT0OcBk3zK
# PqKPNkPFZ360pqA9MtougjZ3xTBb7Afe9nRRMquV2RoFmkkY2otSjdPBFQu5GBlm
# NyTXEzjIQ6tCZlbS0eqdPVrUHHUx9g==
# =Al36
# -----END PGP SIGNATURE-----
# gpg: Signature made Tue 07 Mar 2023 20:45:23 GMT
# gpg: using RSA key 6685AE99E75167BCAFC8DF35FBD0DB095A9E2A44
# gpg: Good signature from "Alex Bennée (Master Work Key) <alex.bennee@linaro.org>" [full]
# Primary key fingerprint: 6685 AE99 E751 67BC AFC8 DF35 FBD0 DB09 5A9E 2A44
* tag 'pull-gdbstub-070323-3' of https://gitlab.com/stsquad/qemu: (30 commits)
gdbstub: move update guest debug to accel ops
gdbstub: Build syscall.c once
stubs: split semihosting_get_target from system only stubs
gdbstub: Adjust gdb_do_syscall to only use uint32_t and uint64_t
gdbstub: Remove gdb_do_syscallv
gdbstub: split out softmmu/user specifics for syscall handling
include: split target_long definition from cpu-defs
testing: probe gdb for supported architectures ahead of time
gdbstub: only compile gdbstub twice for whole build
gdbstub: move syscall handling to new file
gdbstub: move register helpers into standalone include
gdbstub: don't use target_ulong while handling registers
gdbstub: fix address type of gdb_set_cpu_pc
gdbstub: specialise stub_can_reverse
gdbstub: introduce gdb_get_max_cpus
gdbstub: specialise target_memory_rw_debug
gdbstub: specialise handle_query_attached
gdbstub: abstract target specific details from gdb_put_packet_binary
gdbstub: rationalise signal mapping in softmmu
gdbstub: move chunks of user code into own files
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
These inline helpers are all used by target specific code so move them
out of the general header so we don't needlessly pollute the rest of
the API with target specific stuff.
Note we have to include cpu.h in semihosting as it was relying on a
side effect before.
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230302190846.2593720-21-alex.bennee@linaro.org>
Message-Id: <20230303025805.625589-21-richard.henderson@linaro.org>
This is only part of it; we will also need to get the PV back end drivers
to tear down their own mappings (or do it for them, but they kind of need
to stop using the pointers too).
Some more work on the actual PV back ends and xen-bus code is going to be
needed to really make soft reset and migration fully functional, and this
part is the basis for that.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Compute the eflags write mask separately, leaving one call
to the helper. Use tcg_constant_i32.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Translators are no longer required to free tcg temporaries.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Since commit a0e61807a3 ("qapi: Remove QMP events and commands from
user-mode builds") we don't generate the "qapi-commands-machine.h"
header in a user-emulation-only build.
Guard qmp_query_cpu_definitions() within CONFIG_USER_ONLY; move
x86_cpu_class_check_missing_features() closer since it is only used
by this QMP command handler.
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230223155540.30370-3-philmd@linaro.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Since tcg_temp_new is now identical, use that.
In some cases we can avoid a copy from A0 or T0.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
In preparation for returning the number of insns generated
via the same pointer. Adjust only the prototypes so far.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230227135202.9710-23-anjo@rev.ng>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230227135202.9710-11-anjo@rev.ng>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230227135202.9710-8-anjo@rev.ng>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230227135202.9710-3-anjo@rev.ng>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The default number of PIRQs is set to 256 to avoid issues with 32-bit MSI
devices. Allow it to be increased if the user desires.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
The way that Xen handles MSI PIRQs is kind of awful.
There is a special MSI message which targets a PIRQ. The vector in the
low bits of data must be zero. The low 8 bits of the PIRQ# are in the
destination ID field, the extended destination ID field is unused, and
instead the high bits of the PIRQ# are in the high 32 bits of the address.
Using the high bits of the address means that we can't intercept and
translate these messages in kvm_send_msi(), because they won't be caught
by the APIC — addresses like 0x1000fee46000 aren't in the APIC's range.
So we catch them in pci_msi_trigger() instead, and deliver the event
channel directly.
That isn't even the worst part. The worst part is that Xen snoops on
writes to devices' MSI vectors while they are *masked*. When a MSI
message is written which looks like it targets a PIRQ, it remembers
the device and vector for later.
When the guest makes a hypercall to bind that PIRQ# (snooped from a
marked MSI vector) to an event channel port, Xen *unmasks* that MSI
vector on the device. Xen guests using PIRQ delivery of MSI don't
ever actually unmask the MSI for themselves.
Now that this is working we can finally enable XENFEAT_hvm_pirqs and
let the guest use it all.
Tested with passthrough igb and emulated e1000e + AHCI.
CPU0 CPU1
0: 65 0 IO-APIC 2-edge timer
1: 0 14 xen-pirq 1-ioapic-edge i8042
4: 0 846 xen-pirq 4-ioapic-edge ttyS0
8: 1 0 xen-pirq 8-ioapic-edge rtc0
9: 0 0 xen-pirq 9-ioapic-level acpi
12: 257 0 xen-pirq 12-ioapic-edge i8042
24: 9600 0 xen-percpu -virq timer0
25: 2758 0 xen-percpu -ipi resched0
26: 0 0 xen-percpu -ipi callfunc0
27: 0 0 xen-percpu -virq debug0
28: 1526 0 xen-percpu -ipi callfuncsingle0
29: 0 0 xen-percpu -ipi spinlock0
30: 0 8608 xen-percpu -virq timer1
31: 0 874 xen-percpu -ipi resched1
32: 0 0 xen-percpu -ipi callfunc1
33: 0 0 xen-percpu -virq debug1
34: 0 1617 xen-percpu -ipi callfuncsingle1
35: 0 0 xen-percpu -ipi spinlock1
36: 8 0 xen-dyn -event xenbus
37: 0 6046 xen-pirq -msi ahci[0000:00:03.0]
38: 1 0 xen-pirq -msi-x ens4
39: 0 73 xen-pirq -msi-x ens4-rx-0
40: 14 0 xen-pirq -msi-x ens4-rx-1
41: 0 32 xen-pirq -msi-x ens4-tx-0
42: 47 0 xen-pirq -msi-x ens4-tx-1
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
This wires up the basic infrastructure but the actual interrupts aren't
there yet, so don't advertise it to the guest.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Just hook up the basic hypercalls to stubs in xen_evtchn.c for now.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Just the basic shell, with the event channel hookup. It only dumps the
buffer for now; a real ring implmentation will come in a subsequent patch.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Which is used to fetch xenstore PFN and port to be used
by the guest. This is preallocated by the toolstack when
guest will just read those and use it straight away.
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Xen has eight frames at 0xfeff8000 for this; we only really need two for
now and KVM puts the identity map at 0xfeffc000, so limit ourselves to
four.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Introduce support for one shot and periodic mode of Xen PV timers,
whereby timer interrupts come through a special virq event channel
with deadlines being set through:
1) set_timer_op hypercall (only oneshot)
2) vcpu_op hypercall for {set,stop}_{singleshot,periodic}_timer
hypercalls
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
The guest is permitted to specify an arbitrary domain/bus/device/function
and INTX pin from which the callback IRQ shall appear to have come.
In QEMU we can only easily do this for devices that actually exist, and
even that requires us "knowing" that it's a PCMachine in order to find
the PCI root bus — although that's OK really because it's always true.
We also don't get to get notified of INTX routing changes, because we
can't do that as a passive observer; if we try to register a notifier
it will overwrite any existing notifier callback on the device.
But in practice, guests using PCI_INTX will only ever use pin A on the
Xen platform device, and won't swizzle the INTX routing after they set
it up. So this is just fine.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
The GSI callback (and later PCI_INTX) is a level triggered interrupt. It
is asserted when an event channel is delivered to vCPU0, and is supposed
to be cleared when the vcpu_info->evtchn_upcall_pending field for vCPU0
is cleared again.
Thankfully, Xen does *not* assert the GSI if the guest sets its own
evtchn_upcall_pending field; we only need to assert the GSI when we
have delivered an event for ourselves. So that's the easy part, kind of.
There's a slight complexity in that we need to hold the BQL before we
can call qemu_set_irq(), and we definitely can't do that while holding
our own port_lock (because we'll need to take that from the qemu-side
functions that the PV backend drivers will call). So if we end up
wanting to set the IRQ in a context where we *don't* already hold the
BQL, defer to a BH.
However, we *do* need to poll for the evtchn_upcall_pending flag being
cleared. In an ideal world we would poll that when the EOI happens on
the PIC/IOAPIC. That's how it works in the kernel with the VFIO eventfd
pairs — one is used to trigger the interrupt, and the other works in the
other direction to 'resample' on EOI, and trigger the first eventfd
again if the line is still active.
However, QEMU doesn't seem to do that. Even VFIO level interrupts seem
to be supported by temporarily unmapping the device's BARs from the
guest when an interrupt happens, then trapping *all* MMIO to the device
and sending the 'resample' event on *every* MMIO access until the IRQ
is cleared! Maybe in future we'll plumb the 'resample' concept through
QEMU's irq framework but for now we'll do what Xen itself does: just
check the flag on every vmexit if the upcall GSI is known to be
asserted.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
