Messages in this thread | ![/](/images/icornerl.gif) | | From | Saurabh Singh Sengar <> | Subject | Re: [PATCH] x86/ioapic: Don't return 0 as valid virq | Date | Mon, 13 Mar 2023 03:37:44 +0000 |
| |
I just see mail to rahul.tanwar@linux.intel.com is undelivered, shall I still add it in "Cc:" ? Please let me know what we usually do in such cases.
Regards, Saurabh
> -----Original Message----- > From: Saurabh Singh Sengar <ssengar@microsoft.com> > Sent: Monday, March 13, 2023 9:00 AM > To: Borislav Petkov <bp@alien8.de>; Saurabh Sengar > <ssengar@linux.microsoft.com> > Cc: tglx@linutronix.de; mingo@redhat.com; dave.hansen@linux.intel.com; > x86@kernel.org; hpa@zytor.com; johan+linaro@kernel.org; > isaku.yamahata@intel.com; Michael Kelley (LINUX) > <mikelley@microsoft.com>; linux-kernel@vger.kernel.org; > rahul.tanwar@linux.intel.com; andriy.shevchenko@intel.com > Subject: RE: [EXTERNAL] Re: [PATCH] x86/ioapic: Don't return 0 as valid virq > > Cc: rahul.tanwar@linux.intel.com, andriy.shevchenko@intel.com > > Thanks for you comments, please see my responses below. > > > -----Original Message----- > > From: Borislav Petkov <bp@alien8.de> > > Sent: Monday, March 13, 2023 2:10 AM > > To: Saurabh Sengar <ssengar@linux.microsoft.com> > > Cc: tglx@linutronix.de; mingo@redhat.com; dave.hansen@linux.intel.com; > > x86@kernel.org; hpa@zytor.com; johan+linaro@kernel.org; > > isaku.yamahata@intel.com; Michael Kelley (LINUX) > > <mikelley@microsoft.com>; linux-kernel@vger.kernel.org > > Subject: [EXTERNAL] Re: [PATCH] x86/ioapic: Don't return 0 as valid > > virq > > > > On Thu, Mar 02, 2023 at 11:34:46AM -0800, Saurabh Sengar wrote: > > > Zero is invalid virq and should't be returned as a valid value for > > > lower irq bound. If IO-APIC and gsi_top are not initialized return > > > > Why isn't gsi_top initialized? > > > > What is this fixing? > > In the absence of a device tree node for IO-APIC, IO-APIC is not registered, > resulting in uninitialized gsi_top. And in such cases arch_dynirq_lower_bound > will return 0. Returning 0 from this function will allow interrupts to have 0 > assigned as valid irq, which is wrong. In case gsi_top is 0, lower bound of irq > should be derived from 'hint' value passed to function as 'from'. > > I can add above info in commit message, please let me know if anything > more to be added. > > To be specific in our system which is a guest VM we don't need IO-APIC and > hence there is no device tree node for it. It is observed that we get irq 0 > assigned to PCI-MSI. > > > > > Don't be afraid to do > > > > git annotate arch/x86/kernel/apic/io_apic.c > > > > and see which commit added this. This one: > > > > 3e5bedc2c258 ("x86/apic: Fix arch_dynirq_lower_bound() bug for DT > > enabled > > machines") > > > > Now add the folks from this commit to Cc and tell them why in your > > case gsi_top is not initialized and what they're breaking by doing that. > > Thanks. I will add "Fixes:" and "Cc:" tag in next version. > > > > > The more your commit message explains *why* you're fixing something, > > the better it is for the maintainers/reviewers to actually know what to do. > > > > Right now I'm reading this and I'm thinking, random, unjustified change. > > Ignore. > > > > Ok? > > > > Thx. > > > > -- > > Regards/Gruss, > > Boris. > > > > > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpeop > > > l%2F&data=05%7C01%7Cssengar%40microsoft.com%7C0595a41023f849c5ee > b308db > > > 23732cd0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C638142749 > 8888650 > > > 08%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzI > iLCJBTiI > > > 6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=qpOM5MMYpUof > VOaNsp8HxTmv > > %2B80iVn5rFfzNQTlTwLw%3D&reserved=0 > > e.kernel.org%2Ftglx%2Fnotes-about- > > > netiquette&data=05%7C01%7Cssengar%40microsoft.com%7C6e1e0e21051c4 > > > 9c1cfe008db233a0376%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0% > > > 7C638142504360574969%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjA > > > wMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C > > > %7C&sdata=OLdgb1AuLbLvlzucgNFBQEEK6G%2FsFV%2BO2TqT%2FNCujJU%3 > > D&reserved=0
| ![\](/images/icornerr.gif) |