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From: Quentin Perret <qperret@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: android-kvm@google.com, catalin.marinas@arm.com,
	mate.toth-pal@arm.com, tabba@google.com,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, seanjc@google.com,
	kernel-team@android.com, kvmarm@lists.cs.columbia.edu
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
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
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

  reply	other threads:[~2021-03-23  9:47 UTC|newest]

Thread overview: 21+ 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 ` Marc Zyngier
2021-03-22 16:48 ` 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   ` Marc Zyngier
2021-03-22 16:48   ` 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 16:48   ` Marc Zyngier
2021-03-22 16:48   ` Marc Zyngier
2021-03-22 17:40   ` Quentin Perret
2021-03-22 17:40     ` Quentin Perret
2021-03-22 17:40     ` Quentin Perret
2021-03-22 18:37     ` Marc Zyngier
2021-03-22 18:37       ` Marc Zyngier
2021-03-22 18:37       ` Marc Zyngier
2021-03-23  9:47       ` Quentin Perret [this message]
2021-03-23  9:47         ` Quentin Perret
2021-03-23  9:47         ` Quentin Perret
2021-03-22 16:48 ` [PATCH 3/3] KVM: arm64: Drop the CPU_FTR_REG_HYP_COPY infrastructure Marc Zyngier
2021-03-22 16:48   ` Marc Zyngier
2021-03-22 16:48   ` Marc Zyngier

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