From: Quentin Perret <qperret@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: catalin.marinas@arm.com, james.morse@arm.com,
julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com,
android-kvm@google.com, seanjc@google.com, mate.toth-pal@arm.com,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, kernel-team@android.com,
kvmarm@lists.cs.columbia.edu, tabba@google.com, ardb@kernel.org,
mark.rutland@arm.com, dbrazdil@google.com
Subject: Re: [PATCH 2/3] KVM: arm64: Generate final CTR_EL0 value when running in Protected mode
Date: Tue, 23 Mar 2021 09:47:08 +0000 [thread overview]
Message-ID: <YFm5HIC/2Toowhnx@google.com> (raw)
In-Reply-To: <87k0pzghlx.wl-maz@kernel.org>
Hi Marc,
On Monday 22 Mar 2021 at 18:37:14 (+0000), Marc Zyngier wrote:
> Can't say I'm keen on the yucky bit, but here's an alternative (ha!)
> for you:
>
> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
> index 1a4cee7eb3c9..7582c3bd2f05 100644
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -278,6 +278,9 @@ alternative_else
> ldr_l \reg, arm64_ftr_reg_ctrel0 + ARM64_FTR_SYSVAL
> alternative_endif
> #else
> +alternative_if_not ARM64_KVM_PROTECTED_MODE
> + ASM_BUG()
> +alternative_else_nop_endif
> alternative_cb kvm_compute_final_ctr_el0
> movz \reg, #0
> movk \reg, #0, lsl #16
>
> Yes, it is one more instruction, but it is cleaner and allows us to
> from the first patch of the series.
>
> What do you think?
Yes, I think having the ASM_BUG() in this macro is bit nicer and I doubt
the additional nop will make any difference, so this is looking good to
me!
Thanks,
Quentin
next prev parent reply other threads:[~2021-03-23 9:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 16:48 [PATCH 0/3] KVM:arm64: Proposed host stage-2 improvements Marc Zyngier
2021-03-22 16:48 ` [PATCH 1/3] KVM: arm64: Constraint KVM's own __flush_dcache_area to protectected mode Marc Zyngier
2021-03-22 16:48 ` [PATCH 2/3] KVM: arm64: Generate final CTR_EL0 value when running in Protected mode Marc Zyngier
2021-03-22 17:40 ` Quentin Perret
2021-03-22 18:37 ` Marc Zyngier
2021-03-23 9:47 ` Quentin Perret [this message]
2021-03-22 16:48 ` [PATCH 3/3] KVM: arm64: Drop the CPU_FTR_REG_HYP_COPY infrastructure Marc Zyngier
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