Re: [PATCH v3 18/23] arm64: mte: Restore the GCR_EL1 register after a suspend

From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	Will Deacon <will@kernel.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Szabolcs Nagy <szabolcs.nagy@arm.com>,
	Richard Earnshaw <Richard.Earnshaw@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Peter Collingbourne <pcc@google.com>,
	linux-mm@kvack.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH v3 18/23] arm64: mte: Restore the GCR_EL1 register after a suspend
Date: Thu, 23 Apr 2020 16:23:52 +0100	[thread overview]
Message-ID: <20200423152352.GA21616@e121166-lin.cambridge.arm.com> (raw)
In-Reply-To: <20200421142603.3894-19-catalin.marinas@arm.com>

On Tue, Apr 21, 2020 at 03:25:58PM +0100, Catalin Marinas wrote:
> The CPU resume/suspend routines only take care of the common system
> registers. Restore GCR_EL1 in addition via the __cpu_suspend_exit()
> function.
> 
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
> ---
> 
> Notes:
>     New in v3.
> 
>  arch/arm64/include/asm/mte.h | 4 ++++
>  arch/arm64/kernel/mte.c      | 8 ++++++++
>  arch/arm64/kernel/suspend.c  | 4 ++++
>  3 files changed, 16 insertions(+)

Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

> diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
> index 3dc0a7977124..22eb3e06f311 100644
> --- a/arch/arm64/include/asm/mte.h
> +++ b/arch/arm64/include/asm/mte.h
> @@ -12,6 +12,7 @@ int mte_memcmp_pages(const void *page1_addr, const void *page2_addr);
>  #ifdef CONFIG_ARM64_MTE
>  void flush_mte_state(void);
>  void mte_thread_switch(struct task_struct *next);
> +void mte_suspend_exit(void);
>  long set_mte_ctrl(unsigned long arg);
>  long get_mte_ctrl(void);
>  #else
> @@ -21,6 +22,9 @@ static inline void flush_mte_state(void)
>  static inline void mte_thread_switch(struct task_struct *next)
>  {
>  }
> +static inline void mte_suspend_exit(void)
> +{
> +}
>  static inline long set_mte_ctrl(unsigned long arg)
>  {
>  	return 0;
> diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
> index 212b9fac294d..fa4a4196b248 100644
> --- a/arch/arm64/kernel/mte.c
> +++ b/arch/arm64/kernel/mte.c
> @@ -76,6 +76,14 @@ void mte_thread_switch(struct task_struct *next)
>  	update_gcr_el1_excl(next->thread.gcr_incl);
>  }
>  
> +void mte_suspend_exit(void)
> +{
> +	if (!system_supports_mte())
> +		return;
> +
> +	update_gcr_el1_excl(current->thread.gcr_incl);
> +}
> +
>  long set_mte_ctrl(unsigned long arg)
>  {
>  	u64 tcf0;
> diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
> index 9405d1b7f4b0..1d405b73d009 100644
> --- a/arch/arm64/kernel/suspend.c
> +++ b/arch/arm64/kernel/suspend.c
> @@ -9,6 +9,7 @@
>  #include <asm/daifflags.h>
>  #include <asm/debug-monitors.h>
>  #include <asm/exec.h>
> +#include <asm/mte.h>
>  #include <asm/pgtable.h>
>  #include <asm/memory.h>
>  #include <asm/mmu_context.h>
> @@ -74,6 +75,9 @@ void notrace __cpu_suspend_exit(void)
>  	 */
>  	if (arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE)
>  		arm64_set_ssbd_mitigation(false);
> +
> +	/* Restore additional MTE-specific configuration */
> +	mte_suspend_exit();
>  }
>  
>  /*