diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2026-04-23 17:56:13 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@kernel.org> | 2026-05-19 20:25:51 +0200 |
| commit | 5fcc48d521877c5d83828d715c81f4d169ef97f3 (patch) | |
| tree | fb3acffb9d9a41da557185cbb951a637fa2b385e | |
| parent | 0701c9e17bd903d95b2ddf7dd2e1d8be5027f331 (diff) | |
x86/kvm/vmx: Fix VMX vs hrtimer_rearm_deferred()
Vishal reported that KVM unit test 'x2apic' started failing after commit
0e98eb14814e ("entry: Prepare for deferred hrtimer rearming").
The reason is that KVM/VMX is injecting interrupts while it has interrupts
disabled, for a context that will enable interrupts, this means that
regs->flags.X86_EFLAGS_IF == 0 and irqentry_exit() will not do the right
thing.
Notably, irqentry_exit() must not call hrtimer_rearm_deferred() when the return
context does not have IF set, because this will cause problems vs NMIs.
Therefore, fix up the state after the injection.
Fixes: 0e98eb14814e ("entry: Prepare for deferred hrtimer rearming")
Reported-by: "Verma, Vishal L" <vishal.l.verma@intel.com>
Suggested-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: "Verma, Vishal L" <vishal.l.verma@intel.com>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Zhao Liu <zhao1.liu@intel.com>
Tested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://patch.msgid.link/20260423155936.957351833@infradead.org
Closes: https://lore.kernel.org/r/70cd3e97fbb796e2eb2ff8cd4b7614ada05a5f24.camel%40intel.com
| -rw-r--r-- | arch/x86/entry/common.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index b62ac824c1e9..06c7c6ebd6f9 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -2,6 +2,7 @@ #include <linux/entry-common.h> #include <linux/kvm_types.h> +#include <linux/hrtimer_rearm.h> #include <asm/fred.h> #include <asm/desc.h> @@ -27,6 +28,18 @@ noinstr void x86_entry_from_kvm(unsigned int event_type, unsigned int vector) #else idt_entry_from_kvm(vector); #endif + /* + * Strictly speaking, only the NMI path requires noinstr. + */ + instrumentation_begin(); + /* + * KVM/VMX will dispatch from IRQ-disabled but for a context + * that will have IRQs-enabled. This confuses the entry code + * and it will not have reprogrammed the timer. Do so now. + */ + hrtimer_rearm_deferred(); + instrumentation_end(); + return; } |