linux-kernel - Re: [PATCH v3] KVM: arm64: Use BTI for nvhe

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Date:   Wed, 12 Jul 2023 11:44:08 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Linux regressions mailing list <regressions@...ts.linux.dev>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Mostafa Saleh <smostafa@...gle.com>, oliver.upton@...ux.dev,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, tabba@...gle.com, qperret@...gle.com,
        will@...nel.org, catalin.marinas@....com, yuzenghui@...wei.com,
        suzuki.poulose@....com, james.morse@....com, bgardon@...gle.com,
        gshan@...hat.com
Subject: Re: [PATCH v3] KVM: arm64: Use BTI for nvhe

On Wed, 12 Jul 2023 11:34:51 +0100,
"Linux regression tracking (Thorsten Leemhuis)" <regressions@...mhuis.info> wrote:
> 
> [CCing the regression list, as it should be in the loop for regressions:
> https://docs.kernel.org/admin-guide/reporting-regressions.html]
> 
> [TLDR: I'm adding this report to the list of tracked Linux kernel
> regressions; the text you find below is based on a few templates
> paragraphs you might have encountered already in similar form.
> See link in footer if these mails annoy you.]
> 
> On 04.07.23 15:41, Sudeep Holla wrote:
> > On Tue, May 30, 2023 at 03:08:45PM +0000, Mostafa Saleh wrote:
> >> CONFIG_ARM64_BTI_KERNEL compiles the kernel to support ARMv8.5-BTI.
> >> However, the nvhe code doesn't make use of it as it doesn't map any
> >> pages with Guarded Page(GP) bit.
> > [...]
> > I was chasing a bug in linux-next yesterday with protected nVHE(pKVM) and
> > cpuidle enabled. The system fails to boot. I just bisected the issue to this
> > patch and also saw this patch landed in the linus tree yesterday/today.
> > Not sure if this is something to do with the fact that pKVM skips to
> > __kvm_handle_stub_hvc in __host_hvc.
> > 
> > Let me know if you want be to try something.
> 
> Thanks for the report. Seems the fix is slow to progress.

It's not. See [1].

	M.

[1] https://lore.kernel.org/r/20230706152240.685684-1-smostafa@google.com

-- 
Without deviation from the norm, progress is not possible.