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arch-arm, kvm: Handle vcpu2 if more than 256 vCPUs are in use

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According to KVM Docs [1]:

"When KVM_CAP_ARM_IRQ_LINE_LAYOUT_2 is supported, the target vcpu is
identified as (256 * vcpu2_index + vcpu_index). Otherwise, vcpu2_index
must be zero."

The vcpu parameter from the setIntState method is populated with
the gem5 context identifier (ContextID) of a specific PE.
It is not contrained by the 256 vcpu limit, so it can already specify
more than 256 vcpus. We therefore just need to translate/unpack the
value in two indices (vcpu and vcpu2) which will be forwarded to KVM
when raising an IRQ from userspace.

We guard the vcpu2 retrieval with a hash define as this is a late
addition and some older kernels do not define this capability (4.15 as
an example).

[1]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html

Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Change-Id: If0c475dc4a573337edd053020920e9b109d13991
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55964
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
Giacomo Travaglini
2022-01-25 16:17:41 +00:00
parent 469d90cbbe
commit 6cf0e0bcc2
1 changed files with 17 additions and 2 deletions
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19
src/arch/arm/kvm/gic.cc
View File

@@ -91,12 +91,27 @@ void
KvmKernelGic::setIntState(unsigned type, unsigned vcpu, unsigned irq,
bool high)
{
const unsigned vcpu_index = vcpu & 0xff;
const unsigned vcpu2_index = (vcpu >> 8) & 0xff;
#if defined(KVM_CAP_ARM_IRQ_LINE_LAYOUT_2) && defined(KVM_ARM_IRQ_VCPU2_SHIFT)
static const bool vcpu2_enabled = vm.checkExtension(
KVM_CAP_ARM_IRQ_LINE_LAYOUT_2);
uint32_t kvm_vcpu = (vcpu2_index << KVM_ARM_IRQ_VCPU2_SHIFT) |
(vcpu_index << KVM_ARM_IRQ_VCPU_SHIFT);
#else
static const bool vcpu2_enabled = false;
uint32_t kvm_vcpu = (vcpu_index << KVM_ARM_IRQ_VCPU_SHIFT);
#endif
panic_if((!vcpu2_enabled && vcpu2_index) || kvm_vcpu > 0xffff,
"VCPU out of range");
assert(type <= KVM_ARM_IRQ_TYPE_MASK);
assert(vcpu <= KVM_ARM_IRQ_VCPU_MASK);
assert(irq <= KVM_ARM_IRQ_NUM_MASK);
const uint32_t line(
kvm_vcpu |
(type << KVM_ARM_IRQ_TYPE_SHIFT) |
(vcpu << KVM_ARM_IRQ_VCPU_SHIFT) |
(irq << KVM_ARM_IRQ_NUM_SHIFT));
vm.setIRQLine(line, high);