cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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iommu-helpers.h (4871B)


      1/* SPDX-License-Identifier: GPL-2.0 */
      2#include <linux/prefetch.h>
      3
      4/**
      5 * iommu_fill_pdir - Insert coalesced scatter/gather chunks into the I/O Pdir.
      6 * @ioc: The I/O Controller.
      7 * @startsg: The scatter/gather list of coalesced chunks.
      8 * @nents: The number of entries in the scatter/gather list.
      9 * @hint: The DMA Hint.
     10 *
     11 * This function inserts the coalesced scatter/gather list chunks into the
     12 * I/O Controller's I/O Pdir.
     13 */ 
     14static inline unsigned int
     15iommu_fill_pdir(struct ioc *ioc, struct scatterlist *startsg, int nents, 
     16		unsigned long hint,
     17		void (*iommu_io_pdir_entry)(u64 *, space_t, unsigned long,
     18					    unsigned long))
     19{
     20	struct scatterlist *dma_sg = startsg;	/* pointer to current DMA */
     21	unsigned int n_mappings = 0;
     22	unsigned long dma_offset = 0, dma_len = 0;
     23	u64 *pdirp = NULL;
     24
     25	/* Horrible hack.  For efficiency's sake, dma_sg starts one 
     26	 * entry below the true start (it is immediately incremented
     27	 * in the loop) */
     28	 dma_sg--;
     29
     30	while (nents-- > 0) {
     31		unsigned long vaddr;
     32		long size;
     33
     34		DBG_RUN_SG(" %d : %08lx/%05x %p/%05x\n", nents,
     35			   (unsigned long)sg_dma_address(startsg), cnt,
     36			   sg_virt(startsg), startsg->length
     37		);
     38
     39
     40		/*
     41		** Look for the start of a new DMA stream
     42		*/
     43		
     44		if (sg_dma_address(startsg) & PIDE_FLAG) {
     45			u32 pide = sg_dma_address(startsg) & ~PIDE_FLAG;
     46
     47			BUG_ON(pdirp && (dma_len != sg_dma_len(dma_sg)));
     48
     49			dma_sg++;
     50
     51			dma_len = sg_dma_len(startsg);
     52			sg_dma_len(startsg) = 0;
     53			dma_offset = (unsigned long) pide & ~IOVP_MASK;
     54			n_mappings++;
     55#if defined(ZX1_SUPPORT)
     56			/* Pluto IOMMU IO Virt Address is not zero based */
     57			sg_dma_address(dma_sg) = pide | ioc->ibase;
     58#else
     59			/* SBA, ccio, and dino are zero based.
     60			 * Trying to save a few CPU cycles for most users.
     61			 */
     62			sg_dma_address(dma_sg) = pide;
     63#endif
     64			pdirp = &(ioc->pdir_base[pide >> IOVP_SHIFT]);
     65			prefetchw(pdirp);
     66		}
     67		
     68		BUG_ON(pdirp == NULL);
     69		
     70		vaddr = (unsigned long)sg_virt(startsg);
     71		sg_dma_len(dma_sg) += startsg->length;
     72		size = startsg->length + dma_offset;
     73		dma_offset = 0;
     74#ifdef IOMMU_MAP_STATS
     75		ioc->msg_pages += startsg->length >> IOVP_SHIFT;
     76#endif
     77		do {
     78			iommu_io_pdir_entry(pdirp, KERNEL_SPACE, 
     79					    vaddr, hint);
     80			vaddr += IOVP_SIZE;
     81			size -= IOVP_SIZE;
     82			pdirp++;
     83		} while(unlikely(size > 0));
     84		startsg++;
     85	}
     86	return(n_mappings);
     87}
     88
     89
     90/*
     91** First pass is to walk the SG list and determine where the breaks are
     92** in the DMA stream. Allocates PDIR entries but does not fill them.
     93** Returns the number of DMA chunks.
     94**
     95** Doing the fill separate from the coalescing/allocation keeps the
     96** code simpler. Future enhancement could make one pass through
     97** the sglist do both.
     98*/
     99
    100static inline unsigned int
    101iommu_coalesce_chunks(struct ioc *ioc, struct device *dev,
    102		struct scatterlist *startsg, int nents,
    103		int (*iommu_alloc_range)(struct ioc *, struct device *, size_t))
    104{
    105	struct scatterlist *contig_sg;	   /* contig chunk head */
    106	unsigned long dma_offset, dma_len; /* start/len of DMA stream */
    107	unsigned int n_mappings = 0;
    108	unsigned int max_seg_size = min(dma_get_max_seg_size(dev),
    109					(unsigned)DMA_CHUNK_SIZE);
    110	unsigned int max_seg_boundary = dma_get_seg_boundary(dev) + 1;
    111	if (max_seg_boundary)	/* check if the addition above didn't overflow */
    112		max_seg_size = min(max_seg_size, max_seg_boundary);
    113
    114	while (nents > 0) {
    115
    116		/*
    117		** Prepare for first/next DMA stream
    118		*/
    119		contig_sg = startsg;
    120		dma_len = startsg->length;
    121		dma_offset = startsg->offset;
    122
    123		/* PARANOID: clear entries */
    124		sg_dma_address(startsg) = 0;
    125		sg_dma_len(startsg) = 0;
    126
    127		/*
    128		** This loop terminates one iteration "early" since
    129		** it's always looking one "ahead".
    130		*/
    131		while(--nents > 0) {
    132			unsigned long prev_end, sg_start;
    133
    134			prev_end = (unsigned long)sg_virt(startsg) +
    135							startsg->length;
    136
    137			startsg++;
    138			sg_start = (unsigned long)sg_virt(startsg);
    139
    140			/* PARANOID: clear entries */
    141			sg_dma_address(startsg) = 0;
    142			sg_dma_len(startsg) = 0;
    143
    144			/*
    145			** First make sure current dma stream won't
    146			** exceed max_seg_size if we coalesce the
    147			** next entry.
    148			*/   
    149			if (unlikely(ALIGN(dma_len + dma_offset + startsg->length, IOVP_SIZE) >
    150				     max_seg_size))
    151				break;
    152
    153			/*
    154			* Next see if we can append the next chunk (i.e.
    155			* it must end on one page and begin on another, or
    156			* it must start on the same address as the previous
    157			* entry ended.
    158			*/
    159			if (unlikely((prev_end != sg_start) ||
    160				((prev_end | sg_start) & ~PAGE_MASK)))
    161				break;
    162			
    163			dma_len += startsg->length;
    164		}
    165
    166		/*
    167		** End of DMA Stream
    168		** Terminate last VCONTIG block.
    169		** Allocate space for DMA stream.
    170		*/
    171		sg_dma_len(contig_sg) = dma_len;
    172		dma_len = ALIGN(dma_len + dma_offset, IOVP_SIZE);
    173		sg_dma_address(contig_sg) =
    174			PIDE_FLAG 
    175			| (iommu_alloc_range(ioc, dev, dma_len) << IOVP_SHIFT)
    176			| dma_offset;
    177		n_mappings++;
    178	}
    179
    180	return n_mappings;
    181}
    182