From nobody Fri Dec 19 14:28:43 2025 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E834720D502 for ; Tue, 1 Apr 2025 16:43:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743525797; cv=none; b=pK3YRFu1qHUupc8IioiybcWNwK3z0MMNvneuVU4Ax4GEqMTn76AhYiCbB6fl/w4fWAGeZG9bvWP3EHeplrrsPOufCK5VZtA+TncGwQCxrpYpu0vcKMPBQd4Bwivltk7azWcPlcu7qHJtb1G0DNl9Mks0Q32ISi0EUSSbrfT28eA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743525797; c=relaxed/simple; bh=IX2hIEFDZxr1s7mPt549rL+2MP5J40qc7gWfaob7z2I=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=SIeDx+HmqCNe6jOQXA8WeXRXbDEltBULpKqRM6l2Y+Ode6SBrJ3KW11bKxHQzNFrWZIErYWP3PTdvd3grl/XRfTbmHuKD7waaikz8ZyXUH810bXCs/1ZuHnl95t82bE934OVZRssdVPQ+lTw/xhjFITj2oMTPHwh3Br667dBsas= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=2RV4GpZl; arc=none smtp.client-ip=209.85.214.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="2RV4GpZl" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-22651aca434so108953515ad.1 for ; Tue, 01 Apr 2025 09:43:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1743525795; x=1744130595; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=tjqTIWn86XObYZ0dlBWL1fKISTH8kVDuFqpN5liSeqY=; b=2RV4GpZlnot4SCQ5wABLNoj1h5/geg50gJV/aZ0WrLzGYB/VV3xhNfojzwmHO0uDYz g31k7XvWqBamA1iirpWdFwlIerGnukt8vXTN16dbap04aiQd38ioMrYWgU3kFFc5odti G3p58wvcGb0TWKOKcZh4W9l5+3syRSR1wYrrRMdvuji2Yn4VG1pIqMWInZnmw4M6Sezs 7l2ZkZNNoe0TUoaH4AB6Ite60SMnnBmvXQgUhl2So3HEUiHXZv9jlhMmxdb3We6fpkHa 8wqwkYjn53FsRSZfxI7C7rZRuTeCyd7KO4GJrlszzn9sFKa8uVGmvZKcdJaFMIDs46Ln Ejhg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1743525795; x=1744130595; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=tjqTIWn86XObYZ0dlBWL1fKISTH8kVDuFqpN5liSeqY=; b=Ki/PHwKPXGBCrTToVzPBjQFsrOvRNPYJ0ouacuhs0Ph5x8dgBGAluNCaTeNdfRg1sJ RK3sY0Vo9+a2AV+wL3e2Bd4LpCx95rnwoFhLFHkqnuweFUUj/vzYf/Maxdoy1Z2snZNV Dql4TnUvR0tyMZ/+x2K9iUqFoBuDOoiABH7V4sGtbURWrQgGgQRwxnq7xLepAOUWOf/+ cRJGs2kL+I/DG9y7f2i9+P8I2c3s114LauMRD0fy0m3neQUgrTBEGswnDmdYw6Pu3GXh Ve8xfr9nJ4TLXPVZpC7aPKhpYRteDPpTfePZzIOdAqVBRRH3UdwAkgeJZjn1gt7lVVX8 4RpA== X-Gm-Message-State: AOJu0YzRGyrbvkTfoKWSOSk9ZBX/8PyarjfWaeL9JNsumask1ZbvAY6E EBqLDWn+lsmNT00x7mDlPZbEseboX3vMjZEBj3Tx21pBA3g2L0joYqmewTJl3lCvzA64OvGHQZl kJA== X-Google-Smtp-Source: AGHT+IF7k6V4hI9NSmqeQR7Ldpinq9z+9LeYTtWSOW3n7weH2d7MasMbpC1/xTtwiRZrQxL5X02TqjREFfU= X-Received: from pfbhw8.prod.google.com ([2002:a05:6a00:8908:b0:730:7e2d:df69]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:1309:b0:736:450c:fa54 with SMTP id d2e1a72fcca58-7398036acbemr20074041b3a.6.1743525795261; Tue, 01 Apr 2025 09:43:15 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 1 Apr 2025 09:34:40 -0700 In-Reply-To: <20250401163447.846608-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250401163447.846608-1-seanjc@google.com> X-Mailer: git-send-email 2.49.0.472.ge94155a9ec-goog Message-ID: <20250401163447.846608-2-seanjc@google.com> Subject: [PATCH v2 1/8] x86/irq: Ensure initial PIR loads are performed exactly once From: Sean Christopherson To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Sean Christopherson , Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Jim Mattson Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Signed-off-by: Sean Christopherson --- arch/x86/kernel/irq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index feca4f20b06a..85fa2db38dc4 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 =3D false; =20 for (i =3D 0; i < 4; i++) - pir_copy[i] =3D pir[i]; + pir_copy[i] =3D READ_ONCE(pir[i]); =20 for (i =3D 0; i < 4; i++) { if (!pir_copy[i]) --=20 2.49.0.472.ge94155a9ec-goog