Re: [PATCH kernel] powerps/pseries/dma: Add support for 2M IOMMU page size
From: Frederic Barrat <hidden>
Date: 2021-09-29 07:01:49
On 28/09/2021 12:15, Alexey Kardashevskiy wrote:
The upcoming PAPR spec adds a 2M page size, bit 23 right after the 16G page size in the "ibm,query-pe-dma-window" call. This adds support for the new page size. Since the new page size is out of sorted order, this changes the loop to not assume that shift[] is sorted. Signed-off-by: Alexey Kardashevskiy <redacted> ---
Looks ok to me Reviewed-by: Frederic Barrat <redacted>
quoted hunk ↗ jump to hunk
This might not work if PHYP keeps rejecting new window requests for less than 32768 TCEs. This is needed: https://github.com/aik/linux/commit/8cc8fa5ba5b3b4a18efbc9d81d9e5b85ca7c8a95 --- arch/powerpc/platforms/pseries/iommu.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index c741689a5165..237bf405b0cb 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c@@ -1159,14 +1159,15 @@ static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn) /* Return largest page shift based on "IO Page Sizes" output of ibm,query-pe-dma-window. */ static int iommu_get_page_shift(u32 query_page_size) { - /* Supported IO page-sizes according to LoPAR */ + /* Supported IO page-sizes according to LoPAR, note that 2M is out of order */ const int shift[] = { __builtin_ctzll(SZ_4K), __builtin_ctzll(SZ_64K), __builtin_ctzll(SZ_16M), __builtin_ctzll(SZ_32M), __builtin_ctzll(SZ_64M), __builtin_ctzll(SZ_128M), - __builtin_ctzll(SZ_256M), __builtin_ctzll(SZ_16G) + __builtin_ctzll(SZ_256M), __builtin_ctzll(SZ_16G), __builtin_ctzll(SZ_2M) }; int i = ARRAY_SIZE(shift) - 1; + int ret = 0; /* * On LoPAR, ibm,query-pe-dma-window outputs "IO Page Sizes" using a bit field:@@ -1176,11 +1177,10 @@ static int iommu_get_page_shift(u32 query_page_size) */ for (; i >= 0 ; i--) { if (query_page_size & (1 << i)) - return shift[i]; + ret = max(ret, shift[i]); } - /* No valid page size found. */ - return 0; + return ret; } static struct property *ddw_property_create(const char *propname, u32 liobn, u64 dma_addr,