From: David Woodhouse <dwmw2@infradead.org>
To: Sean Christopherson <seanjc@google.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"H . Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"rcu@vger.kernel.org" <rcu@vger.kernel.org>,
"mimoja@mimoja.de" <mimoja@mimoja.de>,
"hewenliang4@huawei.com" <hewenliang4@huawei.com>,
"hushiyuan@huawei.com" <hushiyuan@huawei.com>,
"luolongjun@huawei.com" <luolongjun@huawei.com>,
"hejingxian@huawei.com" <hejingxian@huawei.com>
Subject: Re: [PATCH v3 0/9] Parallel CPU bringup for x86_64
Date: Fri, 28 Jan 2022 21:48:26 +0000 [thread overview]
Message-ID: <76B609E5-0203-4F2A-9348-4E88DC72AAF6@infradead.org> (raw)
In-Reply-To: <YfRi2sY0hVfri5eR@google.com>
On 28 January 2022 21:40:42 GMT, Sean Christopherson <seanjc@google.com> wrote:
>On Fri, Jan 28, 2022, David Woodhouse wrote:
>> On Fri, 2021-12-17 at 14:55 -0600, Tom Lendacky wrote:
>> > On 12/17/21 2:13 PM, David Woodhouse wrote:
>> > > On Fri, 2021-12-17 at 13:46 -0600, Tom Lendacky wrote:
>> > > > There's no WARN or PANIC, just a reset. I can look to try and capture some
>> > > > KVM trace data if that would help. If so, let me know what events you'd
>> > > > like captured.
>> > >
>> > >
>> > > Could start with just kvm_run_exit?
>> > >
>> > > Reason 8 would be KVM_EXIT_SHUTDOWN and would potentially indicate a
>> > > triple fault.
>> >
>> > qemu-system-x86-24093 [005] ..... 1601.759486: kvm_exit: vcpu 112 reason shutdown rip 0xffffffff81070574 info1 0x0000000000000000 info2 0x0000000000000000 intr_info 0x80000b08 error_code 0x00000000
>> >
>> > # addr2line -e woodhouse-build-x86_64/vmlinux 0xffffffff81070574
>> > /root/kernels/woodhouse-build-x86_64/./arch/x86/include/asm/desc.h:272
>> >
>> > Which is: asm volatile("ltr %w0"::"q" (GDT_ENTRY_TSS*8));
>>
>> So, I remain utterly bemused by this, and the Milan *guests* I have
>> access to can't even kexec with a stock kernel; that is also "too fast"
>> and they take a triple fault during the bringup in much the same way —
>> even without my parallel patches, and even going back to fairly old
>> kernels.
>>
>> I wasn't able to follow up with raw serial output during the bringup to
>> pinpoint precisely where it happens, because the VM would tear itself
>> down in response to the triple fault without actually flushing the last
>> virtual serial output :)
>>
>> It would be really useful to get access to a suitable host where I can
>> spawn this in qemu and watch it fail. I am suspecting a chip-specific
>> quirk or bug at this point.
>
>Nope. You missed a spot. This also reproduces on a sufficiently large Intel
>system (and Milan). initial_gs gets overwritten by common_cpu_up(), which leads
>to a CPU getting the wrong MSR_GS_BASE and then the wrong raw_smp_processor_id(),
>resulting in cpu_init_exception_handling() stuffing the wrong GDT and leaving a
>NULL TR descriptor for itself.
>
>You also have a lurking bug in the x2APIC ID handling. Stripping the boot flags
>from the prescribed APICID needs to happen before retrieving the x2APIC ID from
>CPUID, otherwise bits 31:16 of the ID will be lost.
>
>You owe me two beers ;-)
Oh Sean, I love you.
Thanks.
Will update and retest and resend.
next prev parent reply other threads:[~2022-01-28 21:49 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-15 14:56 [PATCH v3 0/9] Parallel CPU bringup for x86_64 David Woodhouse
2021-12-15 14:56 ` [PATCH v3 1/9] x86/apic/x2apic: Fix parallel handling of cluster_mask David Woodhouse
2021-12-15 14:56 ` [PATCH v3 2/9] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> David Woodhouse
2021-12-15 14:56 ` [PATCH v3 3/9] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU David Woodhouse
2021-12-15 14:56 ` [PATCH v3 4/9] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() David Woodhouse
2021-12-15 14:56 ` [PATCH v3 5/9] x86/smpboot: Split up native_cpu_up into separate phases and document them David Woodhouse
2021-12-15 14:56 ` [PATCH v3 6/9] x86/smpboot: Support parallel startup of secondary CPUs David Woodhouse
2021-12-16 14:24 ` Tom Lendacky
2021-12-16 18:24 ` David Woodhouse
2021-12-16 19:00 ` Tom Lendacky
2021-12-16 19:20 ` David Woodhouse
2022-01-29 12:04 ` David Woodhouse
2022-01-31 13:59 ` Borislav Petkov
2022-02-01 10:25 ` David Woodhouse
2022-02-01 10:56 ` Borislav Petkov
2022-02-01 12:39 ` David Woodhouse
2022-02-01 12:56 ` Borislav Petkov
2022-02-01 13:02 ` David Woodhouse
2021-12-15 14:56 ` [PATCH v3 7/9] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel David Woodhouse
2021-12-15 14:56 ` [PATCH v3 8/9] x86/mtrr: Avoid repeated save of MTRRs on boot-time CPU bringup David Woodhouse
2021-12-15 14:56 ` [PATCH v3 9/9] x86/smpboot: Serialize topology updates for secondary bringup David Woodhouse
2021-12-16 16:27 ` [PATCH v3 0/9] Parallel CPU bringup for x86_64 Tom Lendacky
2021-12-16 19:24 ` David Woodhouse
2021-12-16 22:52 ` Tom Lendacky
2021-12-17 0:13 ` David Woodhouse
2021-12-17 10:09 ` Igor Mammedov
2021-12-17 15:40 ` David Woodhouse
2021-12-20 17:10 ` David Woodhouse
2021-12-20 18:54 ` Tom Lendacky
2021-12-20 21:29 ` David Woodhouse
2021-12-20 21:47 ` Tom Lendacky
2021-12-21 22:25 ` Tom Lendacky
2021-12-21 22:33 ` David Woodhouse
2021-12-17 17:48 ` Tom Lendacky
2021-12-17 19:11 ` David Woodhouse
2021-12-17 19:26 ` David Woodhouse
2021-12-17 20:15 ` Tom Lendacky
2021-12-17 19:46 ` Tom Lendacky
2021-12-17 20:13 ` David Woodhouse
2021-12-17 20:55 ` Tom Lendacky
2021-12-17 22:48 ` David Woodhouse
2022-01-28 9:54 ` David Woodhouse
2022-01-28 21:40 ` Sean Christopherson
2022-01-28 21:48 ` David Woodhouse [this message]
2022-01-29 9:22 ` David Woodhouse
2021-12-16 19:52 ` David Woodhouse
2021-12-16 19:55 ` Tom Lendacky
2021-12-16 19:59 ` David Woodhouse
2021-12-27 16:57 ` Paul Menzel
2021-12-28 11:34 ` Paul Menzel
2021-12-28 14:18 ` David Woodhouse
2021-12-29 13:18 ` Paul Menzel
2021-12-29 13:54 ` David Woodhouse
2022-02-14 13:45 ` Paul Menzel
2022-04-21 10:00 ` Mimoja
2022-04-22 21:19 ` Tom Lendacky
2022-06-01 8:30 ` David Woodhouse
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