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From: James Morse <james.morse@arm.com>
To: Julien Thierry <julien.thierry@arm.com>,
	linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, daniel.thompson@linaro.org,
	joel@joelfernandes.org, marc.zyngier@arm.com,
	mark.rutland@arm.com, christoffer.dall@arm.com,
	catalin.marinas@arm.com, will.deacon@arm.com,
	Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: Re: [PATCH v5 02/27] arm64: cpufeature: Use alternatives for VHE cpu_enable
Date: Wed, 12 Sep 2018 11:28:20 +0100	[thread overview]
Message-ID: <1d425320-aed3-b949-1ec5-f378248aac4d@arm.com> (raw)
In-Reply-To: <1535471497-38854-3-git-send-email-julien.thierry@arm.com>

Hi Julien,

On 28/08/18 16:51, Julien Thierry wrote:
> The cpu_enable callback for VHE feature requires all alternatives to have
> been applied. This prevents applying VHE alternative separately from the
> rest.
> 
> Use an alternative depending on VHE feature to know whether VHE
> alternatives have already been applied.

> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 1e433ac..3bc1c8b 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1022,8 +1024,15 @@ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
>  	 * that, freshly-onlined CPUs will set tpidr_el2, so we don't need to
>  	 * do anything here.
>  	 */
> -	if (!alternatives_applied)
> -		write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);
> +	asm volatile(ALTERNATIVE(
> +		"mrs	%0, tpidr_el1\n"
> +		"msr	tpidr_el2, %0",
> +		"nop\n"
> +		"nop",
> +		ARM64_HAS_VIRT_HOST_EXTN)
> +		: "+r" (tmp)
> +		:
> +		: "memory");
>  }
>  #endif

Catalin's preference was to keep this all in C:
https://patchwork.kernel.org/patch/10007977/
, for which we need to know if 'the' alternative has been applied.

I suspect there may be more registers in this list if we have to switch to
another EL2 register using alternatives. (but I don't have an example).

Could we make 'alternatives_applied' a macro that takes the cap as an argument?


Thanks,

James

  reply	other threads:[~2018-09-12 10:28 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-28 15:51 [PATCH v5 00/27] arm64: provide pseudo NMI with GICv3 Julien Thierry
2018-08-28 15:51 ` [PATCH v5 01/27] arm64: cpufeature: Set SYSREG_GIC_CPUIF as a boot system feature Julien Thierry
2018-09-21 15:56   ` Marc Zyngier
     [not found]     ` <MWHPR0601MB3707D7CF3B55BF40EEEA0D52C4160@MWHPR0601MB3707.namprd06.prod.outlook.com>
2018-09-25  8:13       ` Marc Zyngier
2018-08-28 15:51 ` [PATCH v5 02/27] arm64: cpufeature: Use alternatives for VHE cpu_enable Julien Thierry
2018-09-12 10:28   ` James Morse [this message]
2018-09-12 12:03     ` Julien Thierry
2018-09-18 17:46       ` James Morse
2018-09-12 12:37     ` Suzuki K Poulose
2018-08-28 15:51 ` [PATCH v5 03/27] arm64: alternative: Apply alternatives early in boot process Julien Thierry
2018-09-12 10:29   ` James Morse
2018-09-12 16:49     ` Julien Thierry
2018-09-17 23:44       ` Daniel Thompson
2018-09-18  7:37         ` Julien Thierry
2018-09-18 17:47         ` James Morse
2018-09-21 16:05       ` Marc Zyngier
2018-08-28 15:51 ` [PATCH v5 04/27] arm64: daifflags: Use irqflags functions for daifflags Julien Thierry
2018-09-12 12:28   ` James Morse
2018-10-03 15:09   ` Catalin Marinas
2018-08-28 15:51 ` [PATCH v5 05/27] arm64: Use daifflag_restore after bp_hardening Julien Thierry
2018-09-12 10:32   ` James Morse
2018-09-12 11:11     ` Julien Thierry
2018-09-12 12:28       ` James Morse
2018-09-12 13:03         ` Julien Thierry
2018-10-03 15:12   ` Catalin Marinas
2018-08-28 15:51 ` [PATCH v5 06/27] arm64: Delay daif masking for user return Julien Thierry
2018-09-12 10:31   ` James Morse
2018-09-12 13:07     ` Julien Thierry
2018-08-28 15:51 ` [PATCH v5 07/27] arm64: xen: Use existing helper to check interrupt status Julien Thierry
2018-08-29 21:35   ` Stefano Stabellini
2018-10-03 15:14   ` Catalin Marinas
2018-08-28 15:51 ` [PATCH v5 08/27] irqchip/gic: Unify GIC priority definitions Julien Thierry
2018-10-03  9:24   ` Marc Zyngier
2018-08-28 15:51 ` [PATCH v5 09/27] irqchip/gic: Lower priority of GIC interrupts Julien Thierry
2018-08-28 15:51 ` [PATCH v5 10/27] arm64: cpufeature: Add cpufeature for IRQ priority masking Julien Thierry
2018-08-28 15:51 ` [PATCH v5 11/27] arm64: Make PMR part of task context Julien Thierry
2018-08-28 15:51 ` [PATCH v5 12/27] arm64: Unmask PMR before going idle Julien Thierry
2018-08-28 15:51 ` [PATCH v5 13/27] arm/arm64: gic-v3: Add helper functions to manage IRQ priorities Julien Thierry
2018-08-28 15:51 ` [PATCH v5 14/27] arm64: kvm: Unmask PMR before entering guest Julien Thierry
2018-08-28 15:51 ` [PATCH v5 15/27] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking Julien Thierry
2018-09-21 17:39   ` Julien Thierry
2018-09-21 17:55     ` Julien Thierry
2018-08-28 15:51 ` [PATCH v5 16/27] arm64: daifflags: Include PMR in daifflags restore operations Julien Thierry
2018-08-28 15:51 ` [PATCH v5 17/27] irqchip/gic-v3: Factor group0 detection into functions Julien Thierry
2018-08-28 15:51 ` [PATCH v5 18/27] irqchip/gic-v3: Do not overwrite PMR value Julien Thierry
2018-08-28 15:51 ` [PATCH v5 19/27] irqchip/gic-v3: Remove acknowledge loop Julien Thierry
2018-10-03  9:26   ` Marc Zyngier
2018-08-28 15:51 ` [PATCH v5 20/27] irqchip/gic-v3: Switch to PMR masking after IRQ acknowledge Julien Thierry
2018-08-28 15:51 ` [PATCH v5 21/27] arm64: Switch to PMR masking when starting CPUs Julien Thierry
2018-08-28 15:51 ` [PATCH v5 22/27] arm64: Add build option for IRQ masking via priority Julien Thierry
2018-08-28 15:51 ` [PATCH v5 23/27] arm64: Handle serror in NMI context Julien Thierry
2018-08-28 15:51 ` [PATCH v5 24/27] irqchip/gic-v3: Detect current view of GIC priorities Julien Thierry
2018-08-28 15:51 ` [PATCH v5 25/27] irqchip/gic-v3: Add base support for pseudo-NMI Julien Thierry
2018-08-28 15:51 ` [PATCH v5 26/27] irqchip/gic: Add functions to access irq priorities Julien Thierry
2018-08-28 15:51 ` [PATCH v5 27/27] irqchip/gic-v3: Allow interrupts to be set as pseudo-NMI Julien Thierry
2018-08-29 11:37 ` [PATCH v5 00/27] arm64: provide pseudo NMI with GICv3 Daniel Thompson
2018-08-29 12:58   ` Julien Thierry

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