[PATCH] KVM: arm64: Fix CPUHP logic for protected KVM

Raghavendra Rao Ananta
2023-07-19T17:54:08Z

For protected kvm, the CPU hotplug 'down' logic currently brings
down the timer and vGIC, essentially disabling interrupts. However,
because of how the 'kvm_arm_hardware_enabled' flag is designed, it
never re-enables them back on the CPU hotplug 'up' path. Hence,
clean up the logic to maintain the CPU hotplug up/down symmetry.

Fixes: 466d27e48d7c ("KVM: arm64: Simplify the CPUHP logic")
Reported-by: Oliver Upton <oliver.upton@linux.dev>
Suggested-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
arch/arm64/kvm/arm.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index c2c14059f6a8..010ebfa69650 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1867,14 +1867,10 @@ static void _kvm_arch_hardware_enable(void *discard)

int kvm_arch_hardware_enable(void)
{
- int was_enabled = __this_cpu_read(kvm_arm_hardware_enabled);
-
_kvm_arch_hardware_enable(NULL);

- if (!was_enabled) {
- kvm_vgic_cpu_up();
- kvm_timer_cpu_up();
- }
+ kvm_vgic_cpu_up();
+ kvm_timer_cpu_up();

return 0;
}
@@ -1889,10 +1885,8 @@ static void _kvm_arch_hardware_disable(void *discard)

void kvm_arch_hardware_disable(void)
{
- if (__this_cpu_read(kvm_arm_hardware_enabled)) {
- kvm_timer_cpu_down();
- kvm_vgic_cpu_down();
- }
+ kvm_timer_cpu_down();
+ kvm_vgic_cpu_down();

if (!is_protected_kvm_enabled())
_kvm_arch_hardware_disable(NULL);
--
2.41.0.487.g6d72f3e995-goog