diff options
Diffstat (limited to 'arch/x86/mm/mem_encrypt.c')
| -rw-r--r-- | arch/x86/mm/mem_encrypt.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index bc0833713be9..c79e5736ab2b 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -198,6 +198,37 @@ void __init sme_early_init(void) swiotlb_force = SWIOTLB_FORCE; } +void __init sev_setup_arch(void) +{ + phys_addr_t total_mem = memblock_phys_mem_size(); + unsigned long size; + + if (!sev_active()) + return; + + /* + * For SEV, all DMA has to occur via shared/unencrypted pages. + * SEV uses SWIOTLB to make this happen without changing device + * drivers. However, depending on the workload being run, the + * default 64MB of SWIOTLB may not be enough and SWIOTLB may + * run out of buffers for DMA, resulting in I/O errors and/or + * performance degradation especially with high I/O workloads. + * + * Adjust the default size of SWIOTLB for SEV guests using + * a percentage of guest memory for SWIOTLB buffers. + * Also, as the SWIOTLB bounce buffer memory is allocated + * from low memory, ensure that the adjusted size is within + * the limits of low available memory. + * + * The percentage of guest memory used here for SWIOTLB buffers + * is more of an approximation of the static adjustment which + * 64MB for <1G, and ~128M to 256M for 1G-to-4G, i.e., the 6% + */ + size = total_mem * 6 / 100; + size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G); + swiotlb_adjust_size(size); +} + static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc) { pgprot_t old_prot, new_prot; |