diff options
| author | David Woodhouse <dwmw2@infradead.org> | 2020-10-05 15:18:19 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-12-10 12:15:00 -0500 |
| commit | c1bb5418e32ec70c72af332354b5963eab7a5579 (patch) | |
| tree | 5450a1ff1d4fcf48602f1c21e49852c4f9bb7e73 /include | |
| parent | 75b208c28316095c4685e8596ceb9e3f656592e2 (diff) | |
target/i386: Support up to 32768 CPUs without IRQ remapping
The IOAPIC has an 'Extended Destination ID' field in its RTE, which maps
to bits 11-4 of the MSI address. Since those address bits fall within a
given 4KiB page they were historically non-trivial to use on real hardware.
The Intel IOMMU uses the lowest bit to indicate a remappable format MSI,
and then the remaining 7 bits are part of the index.
Where the remappable format bit isn't set, we can actually use the other
seven to allow external (IOAPIC and MSI) interrupts to reach up to 32768
CPUs instead of just the 255 permitted on bare metal.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <78097f9218300e63e751e077a0a5ca029b56ba46.camel@infradead.org>
[Fix UBSAN warning. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/standard-headers/asm-x86/kvm_para.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/standard-headers/asm-x86/kvm_para.h b/include/standard-headers/asm-x86/kvm_para.h index 07877d3295..215d01b4ec 100644 --- a/include/standard-headers/asm-x86/kvm_para.h +++ b/include/standard-headers/asm-x86/kvm_para.h @@ -32,6 +32,7 @@ #define KVM_FEATURE_POLL_CONTROL 12 #define KVM_FEATURE_PV_SCHED_YIELD 13 #define KVM_FEATURE_ASYNC_PF_INT 14 +#define KVM_FEATURE_MSI_EXT_DEST_ID 15 #define KVM_HINTS_REALTIME 0 |