Marc Zyngier 92f35b751c KVM: arm/arm64: vgic: Allow more than 256 vcpus for KVM_IRQ_LINE ... While parts of the VGIC support a large number of vcpus (we bravely allow up to 512), other parts are more limited. One of these limits is visible in the KVM_IRQ_LINE ioctl, which only allows 256 vcpus to be signalled when using the CPU or PPI types. Unfortunately, we've cornered ourselves badly by allocating all the bits in the irq field. Since the irq_type subfield (8 bit wide) is currently only taking the values 0, 1 and 2 (and we have been careful not to allow anything else), let's reduce this field to only 4 bits, and allocate the remaining 4 bits to a vcpu2_index, which acts as a multiplier: vcpu_id = 256 * vcpu2_index + vcpu_index With that, and a new capability (KVM_CAP_ARM_IRQ_LINE_LAYOUT_2) allowing this to be discovered, it becomes possible to inject PPIs to up to 4096 vcpus. But please just don't. Whilst we're there, add a clarification about the use of KVM_IRQ_LINE on arm, which is not completely conditionned by KVM_CAP_IRQCHIP. Reported-by: Zenghui Yu <yuzenghui@huawei.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Zenghui Yu <yuzenghui@huawei.com> Signed-off-by: Marc Zyngier <maz@kernel.org>		2019-09-09 12:29:09 +01:00
..
arm
devices
amd-memory-encryption.rst
api.txt	KVM: arm/arm64: vgic: Allow more than 256 vcpus for KVM_IRQ_LINE	2019-09-09 12:29:09 +01:00
cpuid.rst
halt-polling.txt
hypercalls.txt
index.rst
locking.txt
mmu.txt
msr.txt
nested-vmx.txt
ppc-pv.txt
review-checklist.txt
s390-diag.txt
timekeeping.txt
vcpu-requests.rst