linux-kernel - Re: [PATCH 4.19 65/84] arm64: KVM: Trap VM ops when ARM64_WORKAROUND_CAVIUM_TX2_219

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Date:   Sat, 11 Jan 2020 18:00:19 +0530
From:   Naresh Kamboju <naresh.kamboju@...aro.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     open list <linux-kernel@...r.kernel.org>,
        linux- stable <stable@...r.kernel.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Will Deacon <will@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        lkft-triage@...ts.linaro.org
Subject: Re: [PATCH 4.19 65/84] arm64: KVM: Trap VM ops when
 ARM64_WORKAROUND_CAVIUM_TX2_219_TVM is set

On Sat, 11 Jan 2020 at 15:49, Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> From: Marc Zyngier <marc.zyngier@....com>
>
> commit d3ec3a08fa700c8b46abb137dce4e2514a6f9668 upstream.
>
> In order to workaround the TX2-219 erratum, it is necessary to trap
> TTBRx_EL1 accesses to EL2. This is done by setting HCR_EL2.TVM on
> guest entry, which has the side effect of trapping all the other
> VM-related sysregs as well.
>
> To minimize the overhead, a fast path is used so that we don't
> have to go all the way back to the main sysreg handling code,
> unless the rest of the hypervisor expects to see these accesses.
>
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> Signed-off-by: Will Deacon <will@...nel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

On stable-rc 4.19 all arm64 builds failed due to this error,

arch/arm64/kvm/hyp/switch.c: In function 'handle_tx2_tvm':
arch/arm64/kvm/hyp/switch.c:438:2: error: implicit declaration of
function '__kvm_skip_instr'; did you mean 'kvm_skip_instr'?
[-Werror=implicit-function-declaration]
  __kvm_skip_instr(vcpu);
  ^~~~~~~~~~~~~~~~
  kvm_skip_instr
cc1: some warnings being treated as errors
scripts/Makefile.build:303: recipe for target
'arch/arm64/kvm/hyp/switch.o' failed

Full build log,
https://ci.linaro.org/view/lkft/job/openembedded-lkft-linux-stable-rc-4.19/DISTRO=lkft,MACHINE=hikey,label=docker-lkft/413/consoleText

-- 
Linaro LKFT
https://lkft.linaro.org