Re: [PATCH] ARM64: mmu: fix mmu_early_enable VA->PA mapping

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 18.12.23 13:05, Lior Weintraub wrote:
> From 1b8f4ee9e29e722bbb0b7d0f7fed0ae213ef8637 Mon Sep 17 00:00:00 2001
> From: Lior Weintraub <liorw@pliops.com>
> Date: Mon, 18 Dec 2023 14:01:16 +0200
> Subject: [PATCH] ARM64: mmu: fix mmu_early_enable VA->PA mapping
> 
> Fix the mmu_early_enable function to correctly map 40bits of virtual address into physical address with a 1:1 mapping.
> It uses the init_range function to sets 2 table entries on TTB level0 and then fill level1 with the correct 1:1 mapping.
> 
> Signed-off-by: Lior Weintraub <liorw@pliops.com>

Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de> # Qemu ARM64 Virt

I ran into some warnings when building, for which I sent out a patch
just now. I think Sascha can squash them if there are no further
comments.

Cheers,
Ahmad

> ---
>  arch/arm/cpu/mmu_64.c            | 17 ++++++++++++++++-
>  arch/arm/cpu/mmu_64.h            | 19 +++++++++++++++++--
>  arch/arm/include/asm/pgtable64.h |  1 +
>  3 files changed, 34 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/cpu/mmu_64.c b/arch/arm/cpu/mmu_64.c
> index c6ea63e655..fe5babbfd9 100644
> --- a/arch/arm/cpu/mmu_64.c
> +++ b/arch/arm/cpu/mmu_64.c
> @@ -294,6 +294,19 @@ void dma_flush_range(void *ptr, size_t size)
>  	v8_flush_dcache_range(start, end);
>  }
>  
> +void init_range(void *virt_addr, size_t size)
> +{
> +	uint64_t *ttb = get_ttb();
> +	uint64_t addr = (uint64_t)virt_addr;
> +	while(size) {
> +		early_remap_range((void *)addr, L0_XLAT_SIZE, MAP_UNCACHED);
> +		split_block(ttb,0);
> +		size -= L0_XLAT_SIZE;
> +		addr += L0_XLAT_SIZE;
> +		ttb++;
> +	}
> +}
> +
>  void mmu_early_enable(unsigned long membase, unsigned long memsize)
>  {
>  	int el;
> @@ -308,7 +321,9 @@ void mmu_early_enable(unsigned long membase, unsigned long memsize)
>  
>  	memset((void *)ttb, 0, GRANULE_SIZE);
>  
> -	early_remap_range(0, 1UL << (BITS_PER_VA - 1), MAP_UNCACHED);
> +	// Assume maximum BITS_PER_PA set to 40 bits.
> +	// Set 1:1 mapping of VA->PA. So to cover the full 1TB range we need 2 tables.
> +	init_range(0, 2*L0_XLAT_SIZE);
>  	early_remap_range(membase, memsize - OPTEE_SIZE, MAP_CACHED);
>  	early_remap_range(membase + memsize - OPTEE_SIZE, OPTEE_SIZE, MAP_FAULT);
>  	early_remap_range(PAGE_ALIGN_DOWN((uintptr_t)_stext), PAGE_ALIGN(_etext - _stext), MAP_CACHED);
> diff --git a/arch/arm/cpu/mmu_64.h b/arch/arm/cpu/mmu_64.h
> index e4d81dace4..e3959e4407 100644
> --- a/arch/arm/cpu/mmu_64.h
> +++ b/arch/arm/cpu/mmu_64.h
> @@ -105,12 +105,27 @@ static inline uint64_t level2mask(int level)
>  	return mask;
>  }
>  
> +/**
> + * @brief Returns the TCR (Translation Control Register) value
> + * 
> + * @param el - Exception Level
> + * @param va_bits - Virtual Address bits
> + * @return uint64_t TCR
> + */
>  static inline uint64_t calc_tcr(int el, int va_bits)
>  {
> -	u64 ips;
> -	u64 tcr;
> +	u64 ips; // Intermediate Physical Address Size
> +	u64 tcr; // Translation Control Register
>  
> +#if (BITS_PER_PA == 40)
>  	ips = 2;
> +#elif (BITS_PER_PA == 36)
> +	ips = 1;
> +#elif (BITS_PER_PA == 32)
> +	ips = 0;
> +#else
> +#error "Unsupported"
> +#endif
>  
>  	if (el == 1)
>  		tcr = (ips << 32) | TCR_EPD1_DISABLE;
> diff --git a/arch/arm/include/asm/pgtable64.h b/arch/arm/include/asm/pgtable64.h
> index 21dac30cfe..b88ffe6be5 100644
> --- a/arch/arm/include/asm/pgtable64.h
> +++ b/arch/arm/include/asm/pgtable64.h
> @@ -8,6 +8,7 @@
>  
>  #define VA_START                   0x0
>  #define BITS_PER_VA                48
> +#define BITS_PER_PA                40 // Use 40 Physical address bits
>  
>  /* Granule size of 4KB is being used */
>  #define GRANULE_SIZE_SHIFT         12

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |