[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH 1/3] x86/x2apic: disable x2apic on resume if the kernel expects so
- To: Shashank Balaji <shashank.mahadasyam@xxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, <x86@xxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Suresh Siddha <suresh.b.siddha@xxxxxxxxx>, "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>, Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>, Wei Liu <wei.liu@xxxxxxxxxx>, Dexuan Cui <decui@xxxxxxxxxxxxx>, Long Li <longli@xxxxxxxxxxxxx>, Ajay Kaher <ajay.kaher@xxxxxxxxxxxx>, Alexey Makhalov <alexey.makhalov@xxxxxxxxxxxx>, Broadcom internal kernel review list <bcm-kernel-feedback-list@xxxxxxxxxxxx>, Jan Kiszka <jan.kiszka@xxxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
- From: Sohil Mehta <sohil.mehta@xxxxxxxxx>
- Date: Tue, 3 Feb 2026 13:08:39 -0800
- Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none
- Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=LGlKOzbPKaZ81XQ6QuEHoOFQ+jjciNTqRTj25RwHY50=; b=yyKeOqEZNWbc9JAYo9Q3EboS0liQvxZtn9RHS6+a7eto7qCi/Rnbh1eTJtnwtl2V8N1Ob6h60Ae51TJJ5FPQZV109rsgy40Z/KvvhYeFnvvosJH8nUbu6I/g23bh7xG71HIGPlJhoBSfwhw52fM2QSgSh/phOZ0mAzNzg9wkNuRkOgnecqLpXcf09tohx/jeV9ErYiogit/5vAd2/NeYPEf3PY+OLT7qO3dBJRibCP7RA7CyEIP9r8+5mAf7I5xPonF6VBQSephHFXdIAg5RYiEVCqpkMzOnashmlKTYyj7KTyKUpxHVDFn5/rctfKAq3X/BuA9IV40awvj1/Hdmnw==
- Arc-seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=wBDzqIUeDTf59gn4wD4SI98TY88DBozbvs4GiraMwQaEb4yJok/ZZrVLxYySn+yae3nX7n4lIGuziA38BDi94Ds08fe6hCSUZfnk5It53TJdNumxqRTW/med9jmVprVS1j9NWLT/FQM4xvQ03uGcUP48eKja/DvY1A4DU4V/oEGMoBz3ZA/fSX1Wgq+LIrRmjOlkgIZl1zb/q8PWbQGekySpwxcvfP8RcLy7PYzIAehQGFzk9bwMfmUPlKJSt/83rdcp57CXIkD1Z/uPfUlgku10jOIGgbegNE2jiCaABw/eR6QwIjZNV7+3/TfotLGmjvczwnxjN8qg5pnOhmC+sw==
- Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com;
- Cc: Ingo Molnar <mingo@xxxxxxx>, <linux-kernel@xxxxxxxxxxxxxxx>, <linux-hyperv@xxxxxxxxxxxxxxx>, <virtualization@xxxxxxxxxxxxxxx>, <jailhouse-dev@xxxxxxxxxxxxxxxx>, <kvm@xxxxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Rahul Bukte <rahul.bukte@xxxxxxxx>, "Daniel Palmer" <daniel.palmer@xxxxxxxx>, Tim Bird <tim.bird@xxxxxxxx>, <stable@xxxxxxxxxxxxxxx>
- Delivery-date: Tue, 03 Feb 2026 21:09:21 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index d93f87f29d03..cc64d61f82cf 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -2456,6 +2456,12 @@ static void lapic_resume(void *data)
> if (x2apic_mode) {
> __x2apic_enable();
> } else {
> + /*
> + * x2apic may have been re-enabled by the
> + * firmware on resuming from s2ram
> + */
> + __x2apic_disable();
> +
We should likely only disable x2apic on platforms that support it and
need the disabling. How about?
...
} else {
/*
*
*/
if (x2apic_enabled())
__x2apic_disable();
I considered if an error message should be printed along with this. But,
I am not sure if it can really be called a firmware issue. It's probably
just that newer CPUs might have started defaulting to x2apic on.
Can you specify what platform you are encountering this?
|
