diff options
| author | Ashish Kalra <ashish.kalra@amd.com> | 2020-12-10 01:25:15 +0000 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2020-12-11 15:43:41 -0500 |
| commit | e998879d4fb7991856916972168cf27c0d86ed12 (patch) | |
| tree | 3bc21e9d11a97ea5c686a917cd03f4835d68d9f5 /kernel/dma | |
| parent | 0477e92881850d44910a7e94fc2c46f96faa131f (diff) | |
| download | linux-e998879d4fb7991856916972168cf27c0d86ed12.tar.bz2 | |
x86,swiotlb: Adjust SWIOTLB bounce buffer size for SEV guests
For SEV, all DMA to and from guest has to use shared (un-encrypted) pages.
SEV uses SWIOTLB to make this happen without requiring changes to device
drivers. However, depending on the workload being run, the default 64MB
of it might not be enough and it may run out of buffers to use for DMA,
resulting in I/O errors and/or performance degradation for high
I/O workloads.
Adjust the default size of SWIOTLB for SEV guests using a
percentage of the total memory available to guest for the SWIOTLB buffers.
Adds a new sev_setup_arch() function which is invoked from setup_arch()
and it calls into a new swiotlb generic code function swiotlb_adjust_size()
to do the SWIOTLB buffer adjustment.
v5 fixed build errors and warnings as
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Co-developed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'kernel/dma')
| -rw-r--r-- | kernel/dma/swiotlb.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 781b9dca197c..7c42df6e6100 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -152,8 +152,6 @@ void swiotlb_set_max_segment(unsigned int val) max_segment = rounddown(val, PAGE_SIZE); } -/* default to 64MB */ -#define IO_TLB_DEFAULT_SIZE (64UL<<20) unsigned long swiotlb_size_or_default(void) { unsigned long size; @@ -163,6 +161,24 @@ unsigned long swiotlb_size_or_default(void) return size ? size : (IO_TLB_DEFAULT_SIZE); } +void __init swiotlb_adjust_size(unsigned long new_size) +{ + unsigned long size; + + /* + * If swiotlb parameter has not been specified, give a chance to + * architectures such as those supporting memory encryption to + * adjust/expand SWIOTLB size for their use. + */ + if (!io_tlb_nslabs) { + size = ALIGN(new_size, 1 << IO_TLB_SHIFT); + io_tlb_nslabs = size >> IO_TLB_SHIFT; + io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE); + + pr_info("SWIOTLB bounce buffer size adjusted to %luMB", size >> 20); + } +} + void swiotlb_print_info(void) { unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT; |