ARM: KVM: Run the exit handling code with disabled preemption
It is important to handle the exit code on the same CPU as the guest,
specially as we're accessing resources that are per-CPU (caches,
for exemple).
To achieve this, make the section that encompassing both
__kvm_vcpu_run() and handle_exit().
user_mem_abort() can sleep though (as it calls gfp_to_pfn()), so
preemption has to be reenabled at that stage.
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 13681a1..b96462b 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -522,6 +522,7 @@
update_vttbr(vcpu->kvm);
+ preempt_disable();
local_irq_disable();
kvm_guest_enter();
vcpu->mode = IN_GUEST_MODE;
@@ -540,6 +541,7 @@
trace_kvm_exit(vcpu->arch.regs.pc);
ret = handle_exit(vcpu, run, ret);
+ preempt_enable();
if (ret) {
kvm_err("Error in handle_exit\n");
break;
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 992d39a..ae38c21 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -419,7 +419,9 @@
pfn_t pfn;
int ret;
+ preempt_enable();
pfn = gfn_to_pfn(vcpu->kvm, gfn);
+ preempt_disable();
if (is_error_pfn(pfn)) {
put_page(pfn_to_page(pfn));
