From 2967178d30ee1109979239ff4f2f99f04d77a911 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 1 Apr 2025 09:34:40 -0700 Subject: x86/irq: Ensure initial PIR loads are performed exactly once [ Upstream commit 600e9606046ac3b9b7a3f0500d08a179df84c45e ] Ensure the PIR is read exactly once at the start of handle_pending_pir(), to guarantee that checking for an outstanding posted interrupt in a given chuck doesn't reload the chunk from the "real" PIR. Functionally, a reload is benign, but it would defeat the purpose of pre-loading into a copy. Fixes: 1b03d82ba15e ("x86/irq: Install posted MSI notification handler") Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/20250401163447.846608-2-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Sasha Levin --- arch/x86/kernel/irq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kernel/irq.c') diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index feca4f20b06aa..85fa2db38dc42 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -414,7 +414,7 @@ static __always_inline bool handle_pending_pir(u64 *pir, struct pt_regs *regs) bool handled = false; for (i = 0; i < 4; i++) - pir_copy[i] = pir[i]; + pir_copy[i] = READ_ONCE(pir[i]); for (i = 0; i < 4; i++) { if (!pir_copy[i]) -- cgit v1.2.3