[v3,3/4] arm64: use both ZONE_DMA and ZONE_DMA32
diff mbox series

Message ID 20190902141043.27210-4-nsaenzjulienne@suse.de
State Superseded
Headers show
Series
  • Raspberry Pi 4 DMA addressing support
Related show

Commit Message

Nicolas Saenz Julienne Sept. 2, 2019, 2:10 p.m. UTC
So far all arm64 devices have supported 32 bit DMA masks for their
peripherals. This is not true anymore for the Raspberry Pi 4 as most of
it's peripherals can only address the first GB of memory on a total of
up to 4 GB.

This goes against ZONE_DMA32's intent, as it's expected for ZONE_DMA32
to be addressable with a 32 bit mask. So it was decided to re-introduce
ZONE_DMA in arm64.

ZONE_DMA will contain the lower 1G of memory, which is currently the
memory area addressable by any peripheral on an arm64 device.
ZONE_DMA32 will contain the rest of the 32 bit addressable memory.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

---

Changes in v3:
- Used fixed size ZONE_DMA
- Fix check befor swiotlb_init()

Changes in v2:
- Update comment to reflect new zones split
- ZONE_DMA will never be left empty

 arch/arm64/Kconfig            |  4 +++
 arch/arm64/include/asm/page.h |  2 ++
 arch/arm64/mm/init.c          | 51 ++++++++++++++++++++++++++++-------
 3 files changed, 47 insertions(+), 10 deletions(-)

Comments

Catalin Marinas Sept. 5, 2019, 5:19 p.m. UTC | #1
On Mon, Sep 02, 2019 at 04:10:41PM +0200, Nicolas Saenz Julienne wrote:
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 8956c22634dd..f02a4945aeac 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -50,6 +50,13 @@
>  s64 memstart_addr __ro_after_init = -1;
>  EXPORT_SYMBOL(memstart_addr);
>  
> +/*
> + * We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA covers the first 1G of
> + * memory as some devices, namely the Raspberry Pi 4, have peripherals with
> + * this limited view of the memory. ZONE_DMA32 will cover the rest of the 32
> + * bit addressable memory area.
> + */
> +phys_addr_t arm64_dma_phys_limit __ro_after_init;
>  phys_addr_t arm64_dma32_phys_limit __ro_after_init;
>  
>  #ifdef CONFIG_KEXEC_CORE
> @@ -164,9 +171,9 @@ static void __init reserve_elfcorehdr(void)
>  }
>  #endif /* CONFIG_CRASH_DUMP */
>  /*
> - * Return the maximum physical address for ZONE_DMA32 (DMA_BIT_MASK(32)). It
> - * currently assumes that for memory starting above 4G, 32-bit devices will
> - * use a DMA offset.
> + * Return the maximum physical address for ZONE_DMA32 (DMA_BIT_MASK(32)) and
> + * ZONE_DMA (DMA_BIT_MASK(30)) respectively. It currently assumes that for
> + * memory starting above 4G, 32-bit devices will use a DMA offset.
>   */
>  static phys_addr_t __init max_zone_dma32_phys(void)
>  {
> @@ -174,12 +181,23 @@ static phys_addr_t __init max_zone_dma32_phys(void)
>  	return min(offset + (1ULL << 32), memblock_end_of_DRAM());
>  }
>  
> +static phys_addr_t __init max_zone_dma_phys(void)
> +{
> +	phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, 32);
> +
> +	return min(offset + (1ULL << ARCH_ZONE_DMA_BITS),
> +		   memblock_end_of_DRAM());
> +}

I think we could squash these two functions into a single one with a
"bits" argument that is either 32 or ARCH_ZONE_DMA_BITS.

> +
>  #ifdef CONFIG_NUMA
>  
>  static void __init zone_sizes_init(unsigned long min, unsigned long max)
>  {
>  	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};
>  
> +#ifdef CONFIG_ZONE_DMA
> +	max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit);
> +#endif
>  #ifdef CONFIG_ZONE_DMA32
>  	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(arm64_dma32_phys_limit);
>  #endif
> @@ -195,13 +213,17 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
>  	struct memblock_region *reg;
>  	unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];
>  	unsigned long max_dma32 = min;
> +	unsigned long max_dma = min;
>  
>  	memset(zone_size, 0, sizeof(zone_size));
>  
> -	/* 4GB maximum for 32-bit only capable devices */
> +#ifdef CONFIG_ZONE_DMA
> +	max_dma = PFN_DOWN(arm64_dma_phys_limit);
> +	zone_size[ZONE_DMA] = max_dma - min;
> +#endif
>  #ifdef CONFIG_ZONE_DMA32
>  	max_dma32 = PFN_DOWN(arm64_dma32_phys_limit);
> -	zone_size[ZONE_DMA32] = max_dma32 - min;
> +	zone_size[ZONE_DMA32] = max_dma32 - max_dma;
>  #endif
>  	zone_size[ZONE_NORMAL] = max - max_dma32;

Does this still work if we have ZONE_DMA32 disabled but ZONE_DMA
enabled? You could use a max(max_dma32, max_dma) or just update
max_dma32 to max_dma in the CONFIG_ZONE_DMA block.

> @@ -213,11 +235,17 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
>  
>  		if (start >= max)
>  			continue;
> -
> +#ifdef CONFIG_ZONE_DMA
> +		if (start < max_dma) {
> +			unsigned long dma_end = min_not_zero(end, max_dma);
> +			zhole_size[ZONE_DMA] -= dma_end - start;
> +		}
> +#endif
>  #ifdef CONFIG_ZONE_DMA32
>  		if (start < max_dma32) {
> -			unsigned long dma_end = min(end, max_dma32);
> -			zhole_size[ZONE_DMA32] -= dma_end - start;
> +			unsigned long dma32_end = min(end, max_dma32);
> +			unsigned long dma32_start = max(start, max_dma);
> +			zhole_size[ZONE_DMA32] -= dma32_end - dma32_start;
>  		}
>  #endif
>  		if (end > max_dma32) {

Similar comment here.
Nicolas Saenz Julienne Sept. 5, 2019, 5:28 p.m. UTC | #2
On Thu, 2019-09-05 at 18:19 +0100, Catalin Marinas wrote:
> On Mon, Sep 02, 2019 at 04:10:41PM +0200, Nicolas Saenz Julienne wrote:
> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> > index 8956c22634dd..f02a4945aeac 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -50,6 +50,13 @@
> >  s64 memstart_addr __ro_after_init = -1;
> >  EXPORT_SYMBOL(memstart_addr);
> >  
> > +/*
> > + * We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA covers the first 1G of
> > + * memory as some devices, namely the Raspberry Pi 4, have peripherals with
> > + * this limited view of the memory. ZONE_DMA32 will cover the rest of the
> > 32
> > + * bit addressable memory area.
> > + */
> > +phys_addr_t arm64_dma_phys_limit __ro_after_init;
> >  phys_addr_t arm64_dma32_phys_limit __ro_after_init;
> >  
> >  #ifdef CONFIG_KEXEC_CORE
> > @@ -164,9 +171,9 @@ static void __init reserve_elfcorehdr(void)
> >  }
> >  #endif /* CONFIG_CRASH_DUMP */
> >  /*
> > - * Return the maximum physical address for ZONE_DMA32 (DMA_BIT_MASK(32)).
> > It
> > - * currently assumes that for memory starting above 4G, 32-bit devices will
> > - * use a DMA offset.
> > + * Return the maximum physical address for ZONE_DMA32 (DMA_BIT_MASK(32))
> > and
> > + * ZONE_DMA (DMA_BIT_MASK(30)) respectively. It currently assumes that for
> > + * memory starting above 4G, 32-bit devices will use a DMA offset.
> >   */
> >  static phys_addr_t __init max_zone_dma32_phys(void)
> >  {
> > @@ -174,12 +181,23 @@ static phys_addr_t __init max_zone_dma32_phys(void)
> >  	return min(offset + (1ULL << 32), memblock_end_of_DRAM());
> >  }
> >  
> > +static phys_addr_t __init max_zone_dma_phys(void)
> > +{
> > +	phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, 32);
> > +
> > +	return min(offset + (1ULL << ARCH_ZONE_DMA_BITS),
> > +		   memblock_end_of_DRAM());
> > +}
> 
> I think we could squash these two functions into a single one with a
> "bits" argument that is either 32 or ARCH_ZONE_DMA_BITS.

Hi Catalin, thanks for the review.

Agree, it'll look nicer.

> > +
> >  #ifdef CONFIG_NUMA
> >  
> >  static void __init zone_sizes_init(unsigned long min, unsigned long max)
> >  {
> >  	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};
> >  
> > +#ifdef CONFIG_ZONE_DMA
> > +	max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit);
> > +#endif
> >  #ifdef CONFIG_ZONE_DMA32
> >  	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(arm64_dma32_phys_limit);
> >  #endif
> > @@ -195,13 +213,17 @@ static void __init zone_sizes_init(unsigned long min,
> > unsigned long max)
> >  	struct memblock_region *reg;
> >  	unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];
> >  	unsigned long max_dma32 = min;
> > +	unsigned long max_dma = min;
> >  
> >  	memset(zone_size, 0, sizeof(zone_size));
> >  
> > -	/* 4GB maximum for 32-bit only capable devices */
> > +#ifdef CONFIG_ZONE_DMA
> > +	max_dma = PFN_DOWN(arm64_dma_phys_limit);
> > +	zone_size[ZONE_DMA] = max_dma - min;
> > +#endifmax_dma32
> >  #ifdef CONFIG_ZONE_DMA32
> >  	max_dma32 = PFN_DOWN(arm64_dma32_phys_limit);
> > -	zone_size[ZONE_DMA32] = max_dma32 - min;
> > +	zone_size[ZONE_DMA32] = max_dma32 - max_dma;
> >  #endif
> >  	zone_size[ZONE_NORMAL] = max - max_dma32;
> 
> Does this still work if we have ZONE_DMA32 disabled but ZONE_DMA
> enabled? You could use a max(max_dma32, max_dma) or just update
> max_dma32 to max_dma in the CONFIG_ZONE_DMA block.

You're right, I missed that scenario. I'll fix it and give it a test for the
next series.

Regards,
Nicolas

Patch
diff mbox series

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 3adcec05b1f6..a9fd71d3bc8e 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -266,6 +266,10 @@  config GENERIC_CSUM
 config GENERIC_CALIBRATE_DELAY
 	def_bool y
 
+config ZONE_DMA
+	bool "Support DMA zone" if EXPERT
+	default y
+
 config ZONE_DMA32
 	bool "Support DMA32 zone" if EXPERT
 	default y
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index d39ddb258a04..7b8c98830101 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -38,4 +38,6 @@  extern int pfn_valid(unsigned long);
 
 #include <asm-generic/getorder.h>
 
+#define ARCH_ZONE_DMA_BITS 30
+
 #endif
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 8956c22634dd..f02a4945aeac 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -50,6 +50,13 @@ 
 s64 memstart_addr __ro_after_init = -1;
 EXPORT_SYMBOL(memstart_addr);
 
+/*
+ * We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA covers the first 1G of
+ * memory as some devices, namely the Raspberry Pi 4, have peripherals with
+ * this limited view of the memory. ZONE_DMA32 will cover the rest of the 32
+ * bit addressable memory area.
+ */
+phys_addr_t arm64_dma_phys_limit __ro_after_init;
 phys_addr_t arm64_dma32_phys_limit __ro_after_init;
 
 #ifdef CONFIG_KEXEC_CORE
@@ -164,9 +171,9 @@  static void __init reserve_elfcorehdr(void)
 }
 #endif /* CONFIG_CRASH_DUMP */
 /*
- * Return the maximum physical address for ZONE_DMA32 (DMA_BIT_MASK(32)). It
- * currently assumes that for memory starting above 4G, 32-bit devices will
- * use a DMA offset.
+ * Return the maximum physical address for ZONE_DMA32 (DMA_BIT_MASK(32)) and
+ * ZONE_DMA (DMA_BIT_MASK(30)) respectively. It currently assumes that for
+ * memory starting above 4G, 32-bit devices will use a DMA offset.
  */
 static phys_addr_t __init max_zone_dma32_phys(void)
 {
@@ -174,12 +181,23 @@  static phys_addr_t __init max_zone_dma32_phys(void)
 	return min(offset + (1ULL << 32), memblock_end_of_DRAM());
 }
 
+static phys_addr_t __init max_zone_dma_phys(void)
+{
+	phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, 32);
+
+	return min(offset + (1ULL << ARCH_ZONE_DMA_BITS),
+		   memblock_end_of_DRAM());
+}
+
 #ifdef CONFIG_NUMA
 
 static void __init zone_sizes_init(unsigned long min, unsigned long max)
 {
 	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};
 
+#ifdef CONFIG_ZONE_DMA
+	max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit);
+#endif
 #ifdef CONFIG_ZONE_DMA32
 	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(arm64_dma32_phys_limit);
 #endif
@@ -195,13 +213,17 @@  static void __init zone_sizes_init(unsigned long min, unsigned long max)
 	struct memblock_region *reg;
 	unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];
 	unsigned long max_dma32 = min;
+	unsigned long max_dma = min;
 
 	memset(zone_size, 0, sizeof(zone_size));
 
-	/* 4GB maximum for 32-bit only capable devices */
+#ifdef CONFIG_ZONE_DMA
+	max_dma = PFN_DOWN(arm64_dma_phys_limit);
+	zone_size[ZONE_DMA] = max_dma - min;
+#endif
 #ifdef CONFIG_ZONE_DMA32
 	max_dma32 = PFN_DOWN(arm64_dma32_phys_limit);
-	zone_size[ZONE_DMA32] = max_dma32 - min;
+	zone_size[ZONE_DMA32] = max_dma32 - max_dma;
 #endif
 	zone_size[ZONE_NORMAL] = max - max_dma32;
 
@@ -213,11 +235,17 @@  static void __init zone_sizes_init(unsigned long min, unsigned long max)
 
 		if (start >= max)
 			continue;
-
+#ifdef CONFIG_ZONE_DMA
+		if (start < max_dma) {
+			unsigned long dma_end = min_not_zero(end, max_dma);
+			zhole_size[ZONE_DMA] -= dma_end - start;
+		}
+#endif
 #ifdef CONFIG_ZONE_DMA32
 		if (start < max_dma32) {
-			unsigned long dma_end = min(end, max_dma32);
-			zhole_size[ZONE_DMA32] -= dma_end - start;
+			unsigned long dma32_end = min(end, max_dma32);
+			unsigned long dma32_start = max(start, max_dma);
+			zhole_size[ZONE_DMA32] -= dma32_end - dma32_start;
 		}
 #endif
 		if (end > max_dma32) {
@@ -405,7 +433,9 @@  void __init arm64_memblock_init(void)
 
 	early_init_fdt_scan_reserved_mem();
 
-	/* 4GB maximum for 32-bit only capable devices */
+	if (IS_ENABLED(CONFIG_ZONE_DMA))
+		arm64_dma_phys_limit = max_zone_dma_phys();
+
 	if (IS_ENABLED(CONFIG_ZONE_DMA32))
 		arm64_dma32_phys_limit = max_zone_dma32_phys();
 	else
@@ -417,7 +447,7 @@  void __init arm64_memblock_init(void)
 
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 
-	dma_contiguous_reserve(arm64_dma32_phys_limit);
+	dma_contiguous_reserve(arm64_dma_phys_limit ? : arm64_dma32_phys_limit);
 }
 
 void __init bootmem_init(void)
@@ -521,6 +551,7 @@  static void __init free_unused_memmap(void)
 void __init mem_init(void)
 {
 	if (swiotlb_force == SWIOTLB_FORCE ||
+	    max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT) ||
 	    max_pfn > (arm64_dma32_phys_limit >> PAGE_SHIFT))
 		swiotlb_init(1);
 	else