linux-kernel - Re: [PATCH v3 01/12] KVM: arm64: selftests: Add MMIO readl/writel support

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Date:   Thu, 2 Sep 2021 15:21:12 +0200
From:   Andrew Jones <drjones@...hat.com>
To:     Raghavendra Rao Ananta <rananta@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        kvm@...r.kernel.org, Catalin Marinas <catalin.marinas@....com>,
        Peter Shier <pshier@...gle.com>, linux-kernel@...r.kernel.org,
        Will Deacon <will@...nel.org>, kvmarm@...ts.cs.columbia.edu,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 01/12] KVM: arm64: selftests: Add MMIO readl/writel
 support

On Wed, Sep 01, 2021 at 09:14:01PM +0000, Raghavendra Rao Ananta wrote:
> Define the readl() and writel() functions for the guests to
> access (4-byte) the MMIO region.
> 
> The routines, and their dependents, are inspired from the kernel's
> arch/arm64/include/asm/io.h and arch/arm64/include/asm/barrier.h.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
> ---
>  .../selftests/kvm/include/aarch64/processor.h | 45 ++++++++++++++++++-
>  1 file changed, 44 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
> index c0273aefa63d..3cbaf5c1e26b 100644
> --- a/tools/testing/selftests/kvm/include/aarch64/processor.h
> +++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
> @@ -130,6 +130,49 @@ void vm_install_sync_handler(struct kvm_vm *vm,
>  	val;								  \
>  })
>  
> -#define isb()	asm volatile("isb" : : : "memory")
> +#define isb()		asm volatile("isb" : : : "memory")
> +#define dsb(opt)	asm volatile("dsb " #opt : : : "memory")
> +#define dmb(opt)	asm volatile("dmb " #opt : : : "memory")
> +
> +#define dma_wmb()	dmb(oshst)
> +#define __iowmb()	dma_wmb()
> +
> +#define dma_rmb()	dmb(oshld)
> +
> +#define __iormb(v)							\
> +({									\
> +	unsigned long tmp;						\
> +									\
> +	dma_rmb();							\
> +									\
> +	/*								\
> +	 * Courtesy of arch/arm64/include/asm/io.h:			\
> +	 * Create a dummy control dependency from the IO read to any	\
> +	 * later instructions. This ensures that a subsequent call	\
> +	 * to udelay() will be ordered due to the ISB in __delay().	\

We don't have udelay or __delay yet, but I assume they're coming soon.

> +	 */								\
> +	asm volatile("eor	%0, %1, %1\n"				\
> +		     "cbnz	%0, ."					\
> +		     : "=r" (tmp) : "r" ((unsigned long)(v))		\
> +		     : "memory");					\
> +})
> +
> +static __always_inline void __raw_writel(u32 val, volatile void *addr)
> +{
> +	asm volatile("str %w0, [%1]" : : "rZ" (val), "r" (addr));
> +}
> +
> +static __always_inline u32 __raw_readl(const volatile void *addr)
> +{
> +	u32 val;
> +	asm volatile("ldr %w0, [%1]" : "=r" (val) : "r" (addr));
> +	return val;
> +}
> +
> +#define writel_relaxed(v,c)	((void)__raw_writel((__force u32)cpu_to_le32(v),(c)))
> +#define readl_relaxed(c)	({ u32 __r = le32_to_cpu((__force __le32)__raw_readl(c)); __r; })

Might want to explicitly include linux/types.h for these __force symbols.

> +
> +#define writel(v,c)		({ __iowmb(); writel_relaxed((v),(c));})
> +#define readl(c)		({ u32 __v = readl_relaxed(c); __iormb(__v); __v; })
>  
>  #endif /* SELFTEST_KVM_PROCESSOR_H */
> -- 
> 2.33.0.153.gba50c8fa24-goog

Reviewed-by: Andrew Jones <drjones@...hat.com>

Thanks,
drew

> 
> _______________________________________________
> kvmarm mailing list
> kvmarm@...ts.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
> 

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