Re: [RFC PATCH 09/31] lmb: allow for resizing lmb regions

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

On 07.06.24 20:52, Sughosh Ganu wrote:
> Allow for resizing of LMB regions if the region attributes match. The
> current code returns a failure status on detecting an overlapping
> address. This worked up until now since the LMB calls were not
> persistent and global -- the LMB memory map was specific and private
> to a given caller of the LMB API's.
>
> With the change in the LMB code to make the LMB reservations
> persistent, there needs to be a check on whether the memory region can
> be resized, and then do it if so. To distinguish between memory that
> cannot be resized, add a new flag, LMB_NOOVERWRITE. Reserving a region
> of memory with this attribute would indicate that the region cannot be
> resized.
>
> Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
> ---
>   include/lmb.h |   1 +
>   lib/lmb.c     | 120 ++++++++++++++++++++++++++++++++++++++++++++------
>   2 files changed, 107 insertions(+), 14 deletions(-)
>
> diff --git a/include/lmb.h b/include/lmb.h
> index 03bce2a50c..1d4cd255d2 100644
> --- a/include/lmb.h
> +++ b/include/lmb.h
> @@ -20,6 +20,7 @@
>   enum lmb_flags {
>   	LMB_NONE		= 0x0,
>   	LMB_NOMAP		= 0x4,
> +	LMB_NOOVERWRITE		= 0x8,

Please, add the missing description for the new value. Using the first
available bit (0x01) would be expected.

Using the BIT macro would make it clearer that these are bits of a bitmap:

enum lmb_flags {
	LMB_NONE		= BIT(0),
	LMB_NOOVERWRITE		= BIT(1),
};

Best regards

Heinrich


>   };
>
>   /**
> diff --git a/lib/lmb.c b/lib/lmb.c
> index de5a2cf23b..0a4f3d5bcd 100644
> --- a/lib/lmb.c
> +++ b/lib/lmb.c
> @@ -260,12 +260,88 @@ void lmb_add_memory(struct bd_info *bd)
>   	}
>   }
>
> +static bool lmb_region_flags_match(struct lmb_region *rgn, unsigned long r1,
> +				   enum lmb_flags flags)
> +{
> +	return rgn->region[r1].flags == flags;
> +}
> +
> +static long lmb_merge_overlap_regions(struct lmb_region *rgn, unsigned long i,
> +				      phys_addr_t base, phys_size_t size,
> +				      enum lmb_flags flags)
> +{
> +	phys_size_t rgnsize;
> +	unsigned long rgn_cnt, idx;
> +	phys_addr_t rgnbase, rgnend;
> +	phys_addr_t mergebase, mergeend;
> +
> +	rgn_cnt = 0;
> +	idx = i;
> +	/*
> +	 * First thing to do is to identify how many regions does
> +	 * the requested region overlap.
> +	 * If the flags match, combine all these overlapping
> +	 * regions into a single region, and remove the merged
> +	 * regions.
> +	 */
> +	while (idx < rgn->cnt - 1) {
> +		rgnbase = rgn->region[idx].base;
> +		rgnsize = rgn->region[idx].size;
> +
> +		if (lmb_addrs_overlap(base, size, rgnbase,
> +				      rgnsize)) {
> +			if (!lmb_region_flags_match(rgn, idx, flags))
> +				return -1;
> +			rgn_cnt++;
> +			idx++;
> +		}
> +	}
> +
> +	/* The merged region's base and size */
> +	rgnbase = rgn->region[i].base;
> +	mergebase = min(base, rgnbase);
> +	rgnend = rgn->region[idx].base + rgn->region[idx].size;
> +	mergeend = max(rgnend, (base + size));
> +
> +	rgn->region[i].base = mergebase;
> +	rgn->region[i].size = mergeend - mergebase;
> +
> +	/* Now remove the merged regions */
> +	while (--rgn_cnt)
> +		lmb_remove_region(rgn, i + 1);
> +
> +	return 0;
> +}
> +
> +static long lmb_resize_regions(struct lmb_region *rgn, unsigned long i,
> +			       phys_addr_t base, phys_size_t size,
> +			       enum lmb_flags flags)
> +{
> +	long ret = 0;
> +	phys_addr_t rgnend;
> +
> +	if (i == rgn->cnt - 1 ||
> +		base + size < rgn->region[i + 1].base) {
> +		if (!lmb_region_flags_match(rgn, i, flags))
> +			return -1;
> +
> +		rgnend = rgn->region[i].base + rgn->region[i].size;
> +		rgn->region[i].base = min(base, rgn->region[i].base);
> +		rgnend = max(base + size, rgnend);
> +		rgn->region[i].size = rgnend - rgn->region[i].base;
> +	} else {
> +		ret = lmb_merge_overlap_regions(rgn, i, base, size, flags);
> +	}
> +
> +	return ret;
> +}
> +
>   /* This routine called with relocation disabled. */
>   static long lmb_add_region_flags(struct lmb_region *rgn, phys_addr_t base,
>   				 phys_size_t size, enum lmb_flags flags)
>   {
>   	unsigned long coalesced = 0;
> -	long adjacent, i;
> +	long ret, i;
>
>   	if (rgn->cnt == 0) {
>   		rgn->region[0].base = base;
> @@ -290,23 +366,32 @@ static long lmb_add_region_flags(struct lmb_region *rgn, phys_addr_t base,
>   				return -1; /* regions with new flags */
>   		}
>
> -		adjacent = lmb_addrs_adjacent(base, size, rgnbase, rgnsize);
> -		if (adjacent > 0) {
> +		ret = lmb_addrs_adjacent(base, size, rgnbase, rgnsize);
> +		if (ret > 0) {
>   			if (flags != rgnflags)
>   				break;
>   			rgn->region[i].base -= size;
>   			rgn->region[i].size += size;
>   			coalesced++;
>   			break;
> -		} else if (adjacent < 0) {
> +		} else if (ret < 0) {
>   			if (flags != rgnflags)
>   				break;
>   			rgn->region[i].size += size;
>   			coalesced++;
>   			break;
>   		} else if (lmb_addrs_overlap(base, size, rgnbase, rgnsize)) {
> -			/* regions overlap */
> -			return -1;
> +			if (flags == LMB_NONE) {
> +				ret = lmb_resize_regions(rgn, i, base, size,
> +							 flags);
> +				if (ret < 0)
> +					return -1;
> +
> +				coalesced++;
> +				break;
> +			} else {
> +				return -1;
> +			}
>   		}
>   	}
>
> @@ -448,7 +533,7 @@ static phys_addr_t lmb_align_down(phys_addr_t addr, phys_size_t size)
>   }
>
>   static phys_addr_t __lmb_alloc_base(phys_size_t size, ulong align,
> -				    phys_addr_t max_addr)
> +				    phys_addr_t max_addr, enum lmb_flags flags)
>   {
>   	long i, rgn;
>   	phys_addr_t base = 0;
> @@ -498,7 +583,7 @@ phys_addr_t lmb_alloc_base(phys_size_t size, ulong align, phys_addr_t max_addr)
>   {
>   	phys_addr_t alloc;
>
> -	alloc = __lmb_alloc_base(size, align, max_addr);
> +	alloc = __lmb_alloc_base(size, align, max_addr, LMB_NONE);
>
>   	if (alloc == 0)
>   		printf("ERROR: Failed to allocate 0x%lx bytes below 0x%lx.\n",
> @@ -507,11 +592,8 @@ phys_addr_t lmb_alloc_base(phys_size_t size, ulong align, phys_addr_t max_addr)
>   	return alloc;
>   }
>
> -/*
> - * Try to allocate a specific address range: must be in defined memory but not
> - * reserved
> - */
> -phys_addr_t lmb_alloc_addr(phys_addr_t base, phys_size_t size)
> +static phys_addr_t __lmb_alloc_addr(phys_addr_t base, phys_size_t size,
> +				    enum lmb_flags flags)
>   {
>   	long rgn;
>
> @@ -526,13 +608,23 @@ phys_addr_t lmb_alloc_addr(phys_addr_t base, phys_size_t size)
>   				      lmb.memory.region[rgn].size,
>   				      base + size - 1, 1)) {
>   			/* ok, reserve the memory */
> -			if (lmb_reserve(base, size) >= 0)
> +			if (lmb_reserve_flags(base, size, flags) >= 0)
>   				return base;
>   		}
>   	}
> +
>   	return 0;
>   }
>
> +/*
> + * Try to allocate a specific address range: must be in defined memory but not
> + * reserved
> + */
> +phys_addr_t lmb_alloc_addr(phys_addr_t base, phys_size_t size)
> +{
> +	return __lmb_alloc_addr(base, size, LMB_NONE);
> +}
> +
>   /* Return number of bytes from a given address that are free */
>   phys_size_t lmb_get_free_size(phys_addr_t addr)
>   {