| Message ID | 20201029172550.3523-1-nsaenzjulienne@suse.de (mailing list archive) |
|---|---|
| Headers | show |
| Series | arm64: Default to 32-bit wide ZONE_DMA | expand |
On Thu, Oct 29, 2020 at 06:25:43PM +0100, Nicolas Saenz Julienne wrote: > Ard Biesheuvel (1): > arm64: mm: Set ZONE_DMA size based on early IORT scan > > Nicolas Saenz Julienne (6): > arm64: mm: Move reserve_crashkernel() into mem_init() > arm64: mm: Move zone_dma_bits initialization into zone_sizes_init() > of/address: Introduce of_dma_get_max_cpu_address() > of: unittest: Add test for of_dma_get_max_cpu_address() > arm64: mm: Set ZONE_DMA size based on devicetree's dma-ranges > mm: Remove examples from enum zone_type comment Thanks for putting this together. I had a minor comment but the patches look fine to me. We still need an ack from Rob on the DT patch and I can queue the series for 5.11. Could you please also test the patch below on top of this series? It's the removal of the implied DMA offset in the max_zone_phys() calculation. --------------------------8<----------------------------- From 3ae252d888be4984a612236124f5b099e804c745 Mon Sep 17 00:00:00 2001 From: Catalin Marinas <catalin.marinas@arm.com> Date: Fri, 30 Oct 2020 18:07:34 +0000 Subject: [PATCH] arm64: Ignore any DMA offsets in the max_zone_phys() calculation Currently, the kernel assumes that if RAM starts above 32-bit (or zone_bits), there is still a ZONE_DMA/DMA32 at the bottom of the RAM and such constrained devices have a hardwired DMA offset. In practice, we haven't noticed any such hardware so let's assume that we can expand ZONE_DMA32 to the available memory if no RAM below 4GB. Similarly, ZONE_DMA is expanded to the 4GB limit if no RAM addressable by zone_bits. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> --- arch/arm64/mm/init.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 095540667f0f..362160e16fb2 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -175,14 +175,21 @@ static void __init reserve_elfcorehdr(void) #endif /* CONFIG_CRASH_DUMP */ /* - * Return the maximum physical address for a zone with a given address size - * limit. It currently assumes that for memory starting above 4G, 32-bit - * devices will use a DMA offset. + * Return the maximum physical address for a zone accessible by the given bits + * limit. If the DRAM starts above 32-bit, expand the zone to the maximum + * available memory, otherwise cap it at 32-bit. */ static phys_addr_t __init max_zone_phys(unsigned int zone_bits) { - phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, zone_bits); - return min(offset + (1ULL << zone_bits), memblock_end_of_DRAM()); + phys_addr_t zone_mask = (1ULL << zone_bits) - 1; + phys_addr_t phys_start = memblock_start_of_DRAM(); + + if (!(phys_start & U32_MAX)) + zone_mask = PHYS_ADDR_MAX; + else if (!(phys_start & zone_mask)) + zone_mask = U32_MAX; + + return min(zone_mask + 1, memblock_end_of_DRAM()); } static void __init zone_sizes_init(unsigned long min, unsigned long max)
On Fri, 2020-10-30 at 18:11 +0000, Catalin Marinas wrote: > On Thu, Oct 29, 2020 at 06:25:43PM +0100, Nicolas Saenz Julienne wrote: > > Ard Biesheuvel (1): > > arm64: mm: Set ZONE_DMA size based on early IORT scan > > > > Nicolas Saenz Julienne (6): > > arm64: mm: Move reserve_crashkernel() into mem_init() > > arm64: mm: Move zone_dma_bits initialization into zone_sizes_init() > > of/address: Introduce of_dma_get_max_cpu_address() > > of: unittest: Add test for of_dma_get_max_cpu_address() > > arm64: mm: Set ZONE_DMA size based on devicetree's dma-ranges > > mm: Remove examples from enum zone_type comment > > Thanks for putting this together. I had a minor comment but the patches > look fine to me. We still need an ack from Rob on the DT patch and I can > queue the series for 5.11. I'm preparing a v6 unifying both functions as you suggested. > Could you please also test the patch below on top of this series? It's > the removal of the implied DMA offset in the max_zone_phys() > calculation. Yes, happily. Comments below. > --------------------------8<----------------------------- > From 3ae252d888be4984a612236124f5b099e804c745 Mon Sep 17 00:00:00 2001 > From: Catalin Marinas <catalin.marinas@arm.com> > Date: Fri, 30 Oct 2020 18:07:34 +0000 > Subject: [PATCH] arm64: Ignore any DMA offsets in the max_zone_phys() > calculation > > Currently, the kernel assumes that if RAM starts above 32-bit (or > zone_bits), there is still a ZONE_DMA/DMA32 at the bottom of the RAM and > such constrained devices have a hardwired DMA offset. In practice, we > haven't noticed any such hardware so let's assume that we can expand > ZONE_DMA32 to the available memory if no RAM below 4GB. Similarly, > ZONE_DMA is expanded to the 4GB limit if no RAM addressable by > zone_bits. > > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > --- > arch/arm64/mm/init.c | 17 ++++++++++++----- > 1 file changed, 12 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 095540667f0f..362160e16fb2 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -175,14 +175,21 @@ static void __init reserve_elfcorehdr(void) > #endif /* CONFIG_CRASH_DUMP */ > > /* > - * Return the maximum physical address for a zone with a given address size > - * limit. It currently assumes that for memory starting above 4G, 32-bit > - * devices will use a DMA offset. > + * Return the maximum physical address for a zone accessible by the given bits > + * limit. If the DRAM starts above 32-bit, expand the zone to the maximum > + * available memory, otherwise cap it at 32-bit. > */ > static phys_addr_t __init max_zone_phys(unsigned int zone_bits) > { > - phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, zone_bits); > - return min(offset + (1ULL << zone_bits), memblock_end_of_DRAM()); > + phys_addr_t zone_mask = (1ULL << zone_bits) - 1; Maybe use DMA_BIT_MASK(), instead of the manual calculation? > + phys_addr_t phys_start = memblock_start_of_DRAM(); > + > + if (!(phys_start & U32_MAX)) I'd suggest using 'bigger than' instead of masks. Just to cover ourselves against memory starting at odd locations. Also it'll behaves properly when phys_start is zero (this breaks things on RPi4). > + zone_mask = PHYS_ADDR_MAX; > + else if (!(phys_start & zone_mask)) > + zone_mask = U32_MAX; > + > + return min(zone_mask + 1, memblock_end_of_DRAM()); This + 1 isn't going to play well when zone_mask is PHYS_ADDR_MAX. Regards, Nicolas
On Tue, Nov 03, 2020 at 06:00:33PM +0100, Nicolas Saenz Julienne wrote: > On Fri, 2020-10-30 at 18:11 +0000, Catalin Marinas wrote: > > On Thu, Oct 29, 2020 at 06:25:43PM +0100, Nicolas Saenz Julienne wrote: > > > Ard Biesheuvel (1): > > > arm64: mm: Set ZONE_DMA size based on early IORT scan > > > > > > Nicolas Saenz Julienne (6): > > > arm64: mm: Move reserve_crashkernel() into mem_init() > > > arm64: mm: Move zone_dma_bits initialization into zone_sizes_init() > > > of/address: Introduce of_dma_get_max_cpu_address() > > > of: unittest: Add test for of_dma_get_max_cpu_address() > > > arm64: mm: Set ZONE_DMA size based on devicetree's dma-ranges > > > mm: Remove examples from enum zone_type comment > > > > Thanks for putting this together. I had a minor comment but the patches > > look fine to me. We still need an ack from Rob on the DT patch and I can > > queue the series for 5.11. > > I'm preparing a v6 unifying both functions as you suggested. > > > Could you please also test the patch below on top of this series? It's > > the removal of the implied DMA offset in the max_zone_phys() > > calculation. > > Yes, happily. Comments below. > > > --------------------------8<----------------------------- > > From 3ae252d888be4984a612236124f5b099e804c745 Mon Sep 17 00:00:00 2001 > > From: Catalin Marinas <catalin.marinas@arm.com> > > Date: Fri, 30 Oct 2020 18:07:34 +0000 > > Subject: [PATCH] arm64: Ignore any DMA offsets in the max_zone_phys() > > calculation > > > > Currently, the kernel assumes that if RAM starts above 32-bit (or > > zone_bits), there is still a ZONE_DMA/DMA32 at the bottom of the RAM and > > such constrained devices have a hardwired DMA offset. In practice, we > > haven't noticed any such hardware so let's assume that we can expand > > ZONE_DMA32 to the available memory if no RAM below 4GB. Similarly, > > ZONE_DMA is expanded to the 4GB limit if no RAM addressable by > > zone_bits. > > > > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > > --- > > arch/arm64/mm/init.c | 17 ++++++++++++----- > > 1 file changed, 12 insertions(+), 5 deletions(-) > > > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > > index 095540667f0f..362160e16fb2 100644 > > --- a/arch/arm64/mm/init.c > > +++ b/arch/arm64/mm/init.c > > @@ -175,14 +175,21 @@ static void __init reserve_elfcorehdr(void) > > #endif /* CONFIG_CRASH_DUMP */ > > > > /* > > - * Return the maximum physical address for a zone with a given address size > > - * limit. It currently assumes that for memory starting above 4G, 32-bit > > - * devices will use a DMA offset. > > + * Return the maximum physical address for a zone accessible by the given bits > > + * limit. If the DRAM starts above 32-bit, expand the zone to the maximum > > + * available memory, otherwise cap it at 32-bit. > > */ > > static phys_addr_t __init max_zone_phys(unsigned int zone_bits) > > { > > - phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, zone_bits); > > - return min(offset + (1ULL << zone_bits), memblock_end_of_DRAM()); > > + phys_addr_t zone_mask = (1ULL << zone_bits) - 1; > > Maybe use DMA_BIT_MASK(), instead of the manual calculation? Yes. > > > + phys_addr_t phys_start = memblock_start_of_DRAM(); > > + > > + if (!(phys_start & U32_MAX)) > > I'd suggest using 'bigger than' instead of masks. Just to cover ourselves > against memory starting at odd locations. Also it'll behaves properly when > phys_start is zero (this breaks things on RPi4). Good point. > > + zone_mask = PHYS_ADDR_MAX; > > + else if (!(phys_start & zone_mask)) > > + zone_mask = U32_MAX; > > + > > + return min(zone_mask + 1, memblock_end_of_DRAM()); > > This + 1 isn't going to play well when zone_mask is PHYS_ADDR_MAX. You are right on PHYS_ADDR_MAX overflowing but I'd keep the +1 since memblock_end_of_DRAM() returns the first byte past the accessible range (so exclusive end). I'll tweak this function a bit to avoid the overflow or use the arm64-specific PHYS_MASK (that's never going to be the full 64 bits). Thanks.