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ALSA: memalloc: Workaround for Xen PV

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We change recently the memalloc helper to use
dma_alloc_noncontiguous() and the fallback to get_pages().  Although
lots of issues with IOMMU (or non-IOMMU) have been addressed, but
there seems still a regression on Xen PV.  Interestingly, the only
proper way to work is use dma_alloc_coherent().  The use of
dma_alloc_coherent() for SG buffer was dropped as it's problematic on
IOMMU systems.  OTOH, Xen PV has a different way, and it's fine to use
the dma_alloc_coherent().

This patch is a workaround for Xen PV.  It consists of the following
changes:
- For Xen PV, use only the fallback allocation without
  dma_alloc_noncontiguous()
- In the fallback allocation, use dma_alloc_coherent();
  the DMA address from dma_alloc_coherent() is returned in get_addr
  ops
- The DMA addresses are stored in an array; the first entry stores the
  number of allocated pages in lower bits, which are referred at
  releasing pages again

Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Fixes: a8d302a0b7 ("ALSA: memalloc: Revive x86-specific WC page allocations again")
Fixes: 9736a32513 ("ALSA: memalloc: Don't fall back for SG-buffer with IOMMU")
Link: https://lore.kernel.org/r/87tu256lqs.wl-tiwai@suse.de
Link: https://lore.kernel.org/r/20230125153104.5527-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2023-01-25 16:31:04 +01:00
parent 6a28a25d35
commit 53466ebdec
1 changed files with 68 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

85
sound/core/memalloc.c
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@ -541,16 +541,15 @@ static void *snd_dma_noncontig_alloc(struct snd_dma_buffer *dmab, size_t size)
struct sg_table *sgt;
void *p;
#ifdef CONFIG_SND_DMA_SGBUF
if (cpu_feature_enabled(X86_FEATURE_XENPV))
return snd_dma_sg_fallback_alloc(dmab, size);
#endif
sgt = dma_alloc_noncontiguous(dmab->dev.dev, size, dmab->dev.dir,
DEFAULT_GFP, 0);
#ifdef CONFIG_SND_DMA_SGBUF
if (!sgt && !get_dma_ops(dmab->dev.dev)) {
if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG)
dmab->dev.type = SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK;
else
dmab->dev.type = SNDRV_DMA_TYPE_DEV_SG_FALLBACK;
if (!sgt && !get_dma_ops(dmab->dev.dev))
return snd_dma_sg_fallback_alloc(dmab, size);
}
#endif
if (!sgt)
return NULL;
@ -717,19 +716,38 @@ static const struct snd_malloc_ops snd_dma_sg_wc_ops = {
/* Fallback SG-buffer allocations for x86 */
struct snd_dma_sg_fallback {
bool use_dma_alloc_coherent;
size_t count;
struct page **pages;
/* DMA address array; the first page contains #pages in ~PAGE_MASK */
dma_addr_t *addrs;
};
static void __snd_dma_sg_fallback_free(struct snd_dma_buffer *dmab,
struct snd_dma_sg_fallback *sgbuf)
{
bool wc = dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK;
size_t i;
size_t i, size;
for (i = 0; i < sgbuf->count && sgbuf->pages[i]; i++)
do_free_pages(page_address(sgbuf->pages[i]), PAGE_SIZE, wc);
if (sgbuf->pages && sgbuf->addrs) {
i = 0;
while (i < sgbuf->count) {
if (!sgbuf->pages[i] || !sgbuf->addrs[i])
break;
size = sgbuf->addrs[i] & ~PAGE_MASK;
if (WARN_ON(!size))
break;
if (sgbuf->use_dma_alloc_coherent)
dma_free_coherent(dmab->dev.dev, size << PAGE_SHIFT,
page_address(sgbuf->pages[i]),
sgbuf->addrs[i] & PAGE_MASK);
else
do_free_pages(page_address(sgbuf->pages[i]),
size << PAGE_SHIFT, false);
i += size;
}
}
kvfree(sgbuf->pages);
kvfree(sgbuf->addrs);
kfree(sgbuf);
}
@ -738,24 +756,36 @@ static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size)
struct snd_dma_sg_fallback *sgbuf;
struct page **pagep, *curp;
size_t chunk, npages;
dma_addr_t *addrp;
dma_addr_t addr;
void *p;
bool wc = dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK;
/* correct the type */
if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_SG)
dmab->dev.type = SNDRV_DMA_TYPE_DEV_SG_FALLBACK;
else if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG)
dmab->dev.type = SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK;
sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
if (!sgbuf)
return NULL;
sgbuf->use_dma_alloc_coherent = cpu_feature_enabled(X86_FEATURE_XENPV);
size = PAGE_ALIGN(size);
sgbuf->count = size >> PAGE_SHIFT;
sgbuf->pages = kvcalloc(sgbuf->count, sizeof(*sgbuf->pages), GFP_KERNEL);
if (!sgbuf->pages)
sgbuf->addrs = kvcalloc(sgbuf->count, sizeof(*sgbuf->addrs), GFP_KERNEL);
if (!sgbuf->pages || !sgbuf->addrs)
goto error;
pagep = sgbuf->pages;
chunk = size;
addrp = sgbuf->addrs;
chunk = (PAGE_SIZE - 1) << PAGE_SHIFT; /* to fit in low bits in addrs */
while (size > 0) {
chunk = min(size, chunk);
p = do_alloc_pages(dmab->dev.dev, chunk, &addr, wc);
if (sgbuf->use_dma_alloc_coherent)
p = dma_alloc_coherent(dmab->dev.dev, chunk, &addr, DEFAULT_GFP);
else
p = do_alloc_pages(dmab->dev.dev, chunk, &addr, false);
if (!p) {
if (chunk <= PAGE_SIZE)
goto error;
@ -767,17 +797,25 @@ static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size)
size -= chunk;
/* fill pages */
npages = chunk >> PAGE_SHIFT;
*addrp = npages; /* store in lower bits */
curp = virt_to_page(p);
while (npages--)
while (npages--) {
*pagep++ = curp++;
*addrp++ |= addr;
addr += PAGE_SIZE;
}
}
p = vmap(sgbuf->pages, sgbuf->count, VM_MAP, PAGE_KERNEL);
if (!p)
goto error;
if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK)
set_pages_array_wc(sgbuf->pages, sgbuf->count);
dmab->private_data = sgbuf;
/* store the first page address for convenience */
dmab->addr = snd_sgbuf_get_addr(dmab, 0);
dmab->addr = sgbuf->addrs[0] & PAGE_MASK;
return p;
error:
@ -787,10 +825,23 @@ static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size)
static void snd_dma_sg_fallback_free(struct snd_dma_buffer *dmab)
{
struct snd_dma_sg_fallback *sgbuf = dmab->private_data;
if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG_FALLBACK)
set_pages_array_wb(sgbuf->pages, sgbuf->count);
vunmap(dmab->area);
__snd_dma_sg_fallback_free(dmab, dmab->private_data);
}
static dma_addr_t snd_dma_sg_fallback_get_addr(struct snd_dma_buffer *dmab,
size_t offset)
{
struct snd_dma_sg_fallback *sgbuf = dmab->private_data;
size_t index = offset >> PAGE_SHIFT;
return (sgbuf->addrs[index] & PAGE_MASK) | (offset & ~PAGE_MASK);
}
static int snd_dma_sg_fallback_mmap(struct snd_dma_buffer *dmab,
struct vm_area_struct *area)
{
@ -805,8 +856,8 @@ static const struct snd_malloc_ops snd_dma_sg_fallback_ops = {
.alloc = snd_dma_sg_fallback_alloc,
.free = snd_dma_sg_fallback_free,
.mmap = snd_dma_sg_fallback_mmap,
.get_addr = snd_dma_sg_fallback_get_addr,
/* reuse vmalloc helpers */
.get_addr = snd_dma_vmalloc_get_addr,
.get_page = snd_dma_vmalloc_get_page,
.get_chunk_size = snd_dma_vmalloc_get_chunk_size,
};