From owner-freebsd-stable@freebsd.org Wed Sep 14 12:33:16 2016 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 50FE1BD973C for ; Wed, 14 Sep 2016 12:33:16 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 3B4CC1E9A for ; Wed, 14 Sep 2016 12:33:16 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: by mailman.ysv.freebsd.org (Postfix) id 3A697BD973B; Wed, 14 Sep 2016 12:33:16 +0000 (UTC) Delivered-To: stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 3A139BD9739 for ; Wed, 14 Sep 2016 12:33:16 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from zxy.spb.ru (zxy.spb.ru [195.70.199.98]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id EE9571E99; Wed, 14 Sep 2016 12:33:15 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from slw by zxy.spb.ru with local (Exim 4.86 (FreeBSD)) (envelope-from ) id 1bk9NJ-0000OG-VX; Wed, 14 Sep 2016 15:33:13 +0300 Date: Wed, 14 Sep 2016 15:33:13 +0300 From: Slawa Olhovchenkov To: Andriy Gapon Cc: Konstantin Belousov , stable@FreeBSD.org Subject: Re: X2APIC support Message-ID: <20160914123313.GC2840@zxy.spb.ru> References: <20160913121133.GX34394@zxy.spb.ru> <71a1f864-66de-0010-5024-e8e985f422f4@FreeBSD.org> <20160913124239.GZ34394@zxy.spb.ru> <20160913142118.GA34394@zxy.spb.ru> <37f5cebc-3fa1-9e95-5123-f3d8daa3130a@FreeBSD.org> <20160913152240.GE38409@kib.kiev.ua> <20160914113634.GF38409@kib.kiev.ua> <763df55a-4b69-9f7a-1042-0f631a729881@FreeBSD.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <763df55a-4b69-9f7a-1042-0f631a729881@FreeBSD.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: slw@zxy.spb.ru X-SA-Exim-Scanned: No (on zxy.spb.ru); SAEximRunCond expanded to false X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 14 Sep 2016 12:33:16 -0000 On Wed, Sep 14, 2016 at 03:22:17PM +0300, Andriy Gapon wrote: > On 14/09/2016 14:36, Konstantin Belousov wrote: > > On Tue, Sep 13, 2016 at 06:52:19PM +0300, Andriy Gapon wrote: > >> On 13/09/2016 18:22, Konstantin Belousov wrote: > >>> Any access > >>> to the LAPIC registers page in x2APIC mode faults. > >> > >> Is this a fact? > >> I read the following in the specification: > >> > >> In x2APIC mode, the memory mapped interface is not available and any > >> access to the MMIO interface will behave similar to that of a legacy xAPIC > >> in globally disabled state. > >> > >> But I couldn't find what actually happens for the legacy xAPIC in globally > >> disabled state. For AMD processors it is documented that if xAPIC is disabled > >> then accessing the APIC memory range works the same as accessing the regular > >> memory. That can be different for Intel processors, of course. > > > > Look at the native_lapic_init(), very beginning of the function. If > > x2apic_mode is non-zero, lapic_map is cleared after DMAP page cache > > attributes are changed. > > Right, but we are talking about the case where x2apic_mode *is zero* while the > hardware in x2APIC mode. > > > Right now, if BIOS pass control to OS in x2APIC mode, thinks just work > > because no LAPIC accesses are done until native_lapic_enable_x2apic() is > > called. This just happens, I thought about more organized receipt of the > > current LAPIC mode. Issue is that decision for LAPIC mode is performed > > by madt enumerator which pref. should not read LAPIC config (too early). > > And it is not clear at all, what to do if there is reason to use xAPIC, > > as checked by madt_setup_local(), but we are in x2APIC mode already. > > Yes. As I mentioned earlier we should at least panic with an informative > message. Maybe we could add some code to so something smarter later. > > > Anyway, returning to the original issue, I do not believe that the > > hand-off on that machine occured in the x2APIC mode when X2APIC_OPT_OUT > > is specified. Kernel would fault in that case. > > I think that it should be easy to check that if Slawa is still willing to try > another diagnostic patch. What combination of BIOS setting need? > diff --git a/sys/x86/x86/local_apic.c b/sys/x86/x86/local_apic.c > index 203e9d00e8acc..37ac03fb9d811 100644 > --- a/sys/x86/x86/local_apic.c > +++ b/sys/x86/x86/local_apic.c > @@ -429,6 +429,12 @@ native_lapic_init(vm_paddr_t addr) > if (x2apic_mode) { > native_lapic_enable_x2apic(); > lapic_map = NULL; > + } else if ((cpu_feature2 & CPUID2_X2APIC) != 0) { > + r = rdmsr(MSR_APICBASE); > + printf("MSR_APICBASE = 0x%16jx\n", (uintmax_t)r); > + if ((r & (APICBASE_X2APIC | APICBASE_ENABLED)) == > + (APICBASE_X2APIC | APICBASE_ENABLED)) > + printf("x2APIC is prohibited but turned on by BIOS\n"); > } > > /* Setup the spurious interrupt handler. */ > > > > -- > Andriy Gapon