diff options
| author | Chuyi Zhou <zhouchuyi@bytedance.com> | 2026-07-09 20:29:32 +0800 |
|---|---|---|
| committer | Thomas Gleixner <tglx@kernel.org> | 2026-07-23 12:30:31 +0200 |
| commit | ae397bb32d2a4cb97d93539a5e50d1d081a7569a (patch) | |
| tree | b80af988b065060b0da774da8d6208e6a27fb190 /arch/x86/kernel | |
| parent | ed15468787dd954ecfabe16378e4d27c8a55c430 (diff) | |
| download | linux-next-ae397bb32d2a4cb97d93539a5e50d1d081a7569a.tar.gz linux-next-ae397bb32d2a4cb97d93539a5e50d1d081a7569a.zip | |
x86/kvm: Disable preemption in kvm_flush_tlb_multi()
kvm_flush_tlb_multi() is installed as an x86 PV TLB flush backend, so
flush_tlb_multi() can reach it through pv_ops when running as a KVM
guest.
kvm_flush_tlb_multi() uses the per-CPU scratch cpumask __pv_cpu_mask.
That buffer must remain tied to the current CPU until the mask has been
copied, filtered, and consumed by native_flush_tlb_multi().
The x86/mm callers currently enter flush_tlb_multi() while pinned to a
CPU. To let those callers drop CPU pinning before issuing the remote TLB
flush, each PV backend must protect its own CPU-local scratch state.
Make the KVM backend protect its per-CPU scratch cpumask by disabling
preemption locally. This is harmless with the current callers, where the
preemption disable is nested, and makes the KVM pv_ops dependency
explicit before changing the x86/mm call sites.
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20260709122933.4021501-14-zhouchuyi@bytedance.com
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/kvm.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index dcef84da304b..5b554e480c0e 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -663,8 +663,10 @@ static void kvm_flush_tlb_multi(const struct cpumask *cpumask, u8 state; int cpu; struct kvm_steal_time *src; - struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); + struct cpumask *flushmask; + guard(preempt)(); + flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); cpumask_copy(flushmask, cpumask); /* * We have to call flush only on online vCPUs. And |