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| author | Sean Christopherson <seanjc@google.com> | 2024-01-10 01:39:35 +0100 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-02-23 01:26:26 +0100 |
| commit | 77bcd9e6231a5297ef417a7d7f734d61c2bcceb6 (patch) | |
| tree | cab40abfd19ea43db33e84549d7588a6febd0623 /virt | |
| parent | KVM: x86: Sanity check that kvm_has_noapic_vcpu is zero at module_exit() (diff) | |
| download | linux-77bcd9e6231a5297ef417a7d7f734d61c2bcceb6.tar.xz linux-77bcd9e6231a5297ef417a7d7f734d61c2bcceb6.zip | |
KVM: Add dedicated arch hook for querying if vCPU was preempted in-kernel
Plumb in a dedicated hook for querying whether or not a vCPU was preempted
in-kernel. Unlike literally every other architecture, x86's VMX can check
if a vCPU is in kernel context if and only if the vCPU is loaded on the
current pCPU.
x86's kvm_arch_vcpu_in_kernel() works around the limitation by querying
kvm_get_running_vcpu() and redirecting to vcpu->arch.preempted_in_kernel
as needed. But that's unnecessary, confusing, and fragile, e.g. x86 has
had at least one bug where KVM incorrectly used a stale
preempted_in_kernel.
No functional change intended.
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Link: https://lore.kernel.org/r/20240110003938.490206-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/kvm_main.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 10bfc88a69f7..9b92858c8b72 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4042,6 +4042,18 @@ static bool vcpu_dy_runnable(struct kvm_vcpu *vcpu) return false; } +/* + * By default, simply query the target vCPU's current mode when checking if a + * vCPU was preempted in kernel mode. All architectures except x86 (or more + * specifical, except VMX) allow querying whether or not a vCPU is in kernel + * mode even if the vCPU is NOT loaded, i.e. using kvm_arch_vcpu_in_kernel() + * directly for cross-vCPU checks is functionally correct and accurate. + */ +bool __weak kvm_arch_vcpu_preempted_in_kernel(struct kvm_vcpu *vcpu) +{ + return kvm_arch_vcpu_in_kernel(vcpu); +} + bool __weak kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu) { return false; @@ -4080,7 +4092,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode) continue; if (READ_ONCE(vcpu->preempted) && yield_to_kernel_mode && !kvm_arch_dy_has_pending_interrupt(vcpu) && - !kvm_arch_vcpu_in_kernel(vcpu)) + !kvm_arch_vcpu_preempted_in_kernel(vcpu)) continue; if (!kvm_vcpu_eligible_for_directed_yield(vcpu)) continue; |