On 03.12.21 04:35, Gavin Shan wrote: > The default block size is same as to the THP size, which is either > retrieved from "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size" > or hardcoded to 2MB. There are flaws in both mechanisms and this > intends to fix them up. > > * When "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size" is > used to getting the THP size, 32MB and 512MB are valid values > when we have 16KB and 64KB page size on ARM64.
Ah, right, there is 16KB as well :) > > * When the hardcoded THP size is used, 2MB, 32MB and 512MB are > valid values when we have 4KB, 16KB and 64KB page sizes on > ARM64. > > Co-developed-by: David Hildenbrand <da...@redhat.com> > Signed-off-by: Gavin Shan <gs...@redhat.com> > --- > hw/virtio/virtio-mem.c | 32 ++++++++++++++++++++------------ > 1 file changed, 20 insertions(+), 12 deletions(-) > > diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c > index ac7a40f514..8f3c95300f 100644 > --- a/hw/virtio/virtio-mem.c > +++ b/hw/virtio/virtio-mem.c > @@ -38,14 +38,25 @@ > */ > #define VIRTIO_MEM_MIN_BLOCK_SIZE ((uint32_t)(1 * MiB)) > > -#if defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) || \ > - defined(__powerpc64__) > -#define VIRTIO_MEM_DEFAULT_THP_SIZE ((uint32_t)(2 * MiB)) > -#else > - /* fallback to 1 MiB (e.g., the THP size on s390x) */ > -#define VIRTIO_MEM_DEFAULT_THP_SIZE VIRTIO_MEM_MIN_BLOCK_SIZE > +static uint32_t virtio_mem_default_thp_size(void) > +{ > + uint32_t default_thp_size = VIRTIO_MEM_MIN_BLOCK_SIZE; > + > +#if defined(__x86_64__) || defined(__arm__) || defined(__powerpc64__) > + default_thp_size = (uint32_t)(2 * MiB); > +#elif defined(__aarch64__) > + if (qemu_real_host_page_size == (4 * KiB)) { you can drop the superfluous (), also in the cases below. > + default_thp_size = (uint32_t)(2 * MiB); The explicit cast shouldn't be required. > + } else if (qemu_real_host_page_size == (16 * KiB)) { > + default_thp_size = (uint32_t)(32 * MiB); > + } else if (qemu_real_host_page_size == (64 * KiB)) { > + default_thp_size = (uint32_t)(512 * MiB); > + } > #endif > > + return default_thp_size; > +} > + > /* > * We want to have a reasonable default block size such that > * 1. We avoid splitting THPs when unplugging memory, which degrades > @@ -78,11 +89,8 @@ static uint32_t virtio_mem_thp_size(void) > if (g_file_get_contents(HPAGE_PMD_SIZE_PATH, &content, NULL, NULL) && > !qemu_strtou64(content, &endptr, 0, &tmp) && > (!endptr || *endptr == '\n')) { > - /* > - * Sanity-check the value, if it's too big (e.g., aarch64 with 64k > base > - * pages) or weird, fallback to something smaller. > - */ > - if (!tmp || !is_power_of_2(tmp) || tmp > 16 * MiB) { > + /* Sanity-check the value and fallback to something reasonable. */ > + if (!tmp || !is_power_of_2(tmp)) { > warn_report("Read unsupported THP size: %" PRIx64, tmp); > } else { > thp_size = tmp; > @@ -90,7 +98,7 @@ static uint32_t virtio_mem_thp_size(void) > } > > if (!thp_size) { > - thp_size = VIRTIO_MEM_DEFAULT_THP_SIZE; > + thp_size = virtio_mem_default_thp_size(); > warn_report("Could not detect THP size, falling back to %" PRIx64 > " MiB.", thp_size / MiB); > } > Apart from that, Reviewed-by: David Hildenbrand <da...@redhat.com> Thanks! -- Thanks, David / dhildenb