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From: Borislav Petkov <bp@alien8.de>
To: Hugh Dickins <hughd@google.com>
Cc: Babu Moger <babu.moger@amd.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Jim Mattson <jmattson@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	kvm list <kvm@vger.kernel.org>, Joerg Roedel <joro@8bytes.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Makarand Sonare <makarandsonare@google.com>,
	Sean Christopherson <seanjc@google.com>
Subject: Re: [PATCH v6 00/12] SVM cleanup and INVPCID feature support
Date: Thu, 25 Mar 2021 10:56:19 +0100	[thread overview]
Message-ID: <20210325095619.GC31322@zn.tnic> (raw)
In-Reply-To: <alpine.LSU.2.11.2103241913190.10112@eggly.anvils>

On Wed, Mar 24, 2021 at 07:43:29PM -0700, Hugh Dickins wrote:
> Right, after looking into it more, I completely agree with you:
> the Kaiser series (in both 4.4-stable and 4.9-stable) was simply
> wrong to lose that invlpg - fine in the kaiser case when we don't
> enable Globals at all, but plain wrong in the !kaiser_enabled case.
> One way or another, we have somehow got away with it for three years.

Yeah, because there were no boxes with kaiser_enabled=0 *and* PCID
which would set INVPCID_SINGLE. Before those, it would INVLPG in the
!INVPCID_SINGLE case.

Oh, btw, booting with "pci=on" "fixes" the issue too. And I tried
reproducing this on an Intel box with "pti=off" but it booted fine
so I'm probably missing some other aspect or triggering it there is
harder/different due to TLB differences or whatnot.

And Babu triggered the same issue on a AMD baremetal yesterday.

> I do agree with Paolo that the PCID_ASID_KERN flush would be better
> moved under the "if (kaiser_enabled)" now.

Ok.

> (And if this were ongoing development, I'd want to rewrite the
> function altogether: but no, these old stable trees are not the place
> for that.)

Bah, it brought some very mixed memories, wading through that code
after years. And yeah, people should stop using all these dead kernels
already! So yeah, no, you don't want to clean up stuff there - let
sleeping dogs lie.

> Boris, may I leave both -stable fixes to you?
> Let me know if you'd prefer me to clean up my mess.

No worries, I'll take care of it.

> Thanks a lot for tracking this down,

Thanks for double-checking me so quickly, lemme whip up a patch.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2021-03-25  9:57 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-11 19:27 [PATCH v6 00/12] SVM cleanup and INVPCID feature support Babu Moger
2020-09-11 19:27 ` [PATCH v6 01/12] KVM: SVM: Introduce vmcb_(set_intercept/clr_intercept/_is_intercept) Babu Moger
2020-09-11 19:28 ` [PATCH v6 02/12] KVM: SVM: Change intercept_cr to generic intercepts Babu Moger
2020-09-11 19:28 ` [PATCH v6 03/12] KVM: SVM: Change intercept_dr " Babu Moger
2020-09-11 19:28 ` [PATCH v6 04/12] KVM: SVM: Modify intercept_exceptions " Babu Moger
2020-09-12 16:52   ` Paolo Bonzini
2020-09-14 15:06     ` Sean Christopherson
2020-09-22 13:39       ` Paolo Bonzini
2020-09-22 19:11         ` Babu Moger
2020-09-23  2:43           ` Paolo Bonzini
2020-09-23 13:35             ` Babu Moger
2020-09-11 19:28 ` [PATCH v6 05/12] KVM: SVM: Modify 64 bit intercept field to two 32 bit vectors Babu Moger
2020-09-11 19:28 ` [PATCH v6 06/12] KVM: SVM: Add new intercept vector in vmcb_control_area Babu Moger
2020-09-11 19:28 ` [PATCH v6 07/12] KVM: nSVM: Cleanup nested_state data structure Babu Moger
2020-09-11 19:28 ` [PATCH v6 08/12] KVM: SVM: Remove set_cr_intercept, clr_cr_intercept and is_cr_intercept Babu Moger
2020-09-11 19:28 ` [PATCH v6 09/12] KVM: SVM: Remove set_exception_intercept and clr_exception_intercept Babu Moger
2020-09-11 19:29 ` [PATCH v6 10/12] KVM: X86: Rename and move the function vmx_handle_memory_failure to x86.c Babu Moger
2020-09-11 19:29 ` [PATCH v6 11/12] KVM: X86: Move handling of INVPCID types to x86 Babu Moger
2020-09-11 19:29 ` [PATCH v6 12/12] KVM:SVM: Enable INVPCID feature on AMD Babu Moger
2020-09-12 17:08 ` [PATCH v6 00/12] SVM cleanup and INVPCID feature support Paolo Bonzini
2020-09-14 15:05   ` Sean Christopherson
2020-09-14 18:33   ` Babu Moger
2021-01-19 23:01     ` Jim Mattson
2021-01-19 23:45       ` Babu Moger
2021-01-20 21:14         ` Jim Mattson
2021-01-20 21:45           ` Babu Moger
2021-01-21  3:10             ` Babu Moger
2021-01-21 23:51               ` Babu Moger
2021-01-23  1:52                 ` Babu Moger
2021-02-24  0:13                   ` Jim Mattson
2021-02-24 22:17                     ` Babu Moger
2021-03-10  1:04                       ` Babu Moger
2021-03-10  9:08                         ` Paolo Bonzini
2021-03-10 14:55                           ` Babu Moger
2021-03-10 14:58                             ` Babu Moger
2021-03-10 15:31                               ` Paolo Bonzini
2021-03-11  1:21                                 ` Babu Moger
2021-03-11 20:07                                   ` Borislav Petkov
2021-03-11 20:32                                     ` Borislav Petkov
2021-03-11 20:57                                       ` Babu Moger
2021-03-11 21:40                                         ` Borislav Petkov
2021-03-11 22:04                                           ` Babu Moger
2021-03-11 22:15                                             ` Babu Moger
2021-03-11 23:52                                               ` Borislav Petkov
2021-03-12 14:53                                                 ` Babu Moger
2021-03-12 16:12                                                 ` Babu Moger
2021-03-24 21:21                                                   ` Borislav Petkov
2021-03-24 21:59                                                     ` Paolo Bonzini
2021-03-25  0:05                                                     ` Hugh Dickins
2021-03-25  2:43                                                       ` Hugh Dickins
2021-03-25  9:56                                                         ` Borislav Petkov [this message]
2021-03-25 10:29                                                           ` [PATCH] x86/tlb: Flush global mappings when KAISER is disabled Borislav Petkov
2021-03-25 10:52                                                             ` Paolo Bonzini
2021-03-25 15:13                                                             ` Babu Moger
2021-03-25 16:33                                                             ` Hugh Dickins
2021-03-25 19:00                                                               ` Jim Mattson
2021-03-25 20:09                                                             ` Borislav Petkov
2021-03-25 20:36                                                               ` Sasha Levin
2021-03-25 23:19                                                                 ` Sasha Levin
2021-03-25 23:56                                                                   ` Ben Hutchings
2021-03-11 21:23                                       ` [PATCH v6 00/12] SVM cleanup and INVPCID feature support Jim Mattson
2021-03-11 21:36                                         ` Borislav Petkov
2021-03-11 21:50                                           ` Babu Moger

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