On 15.11.23 08:14, Xiaoyao Li wrote:
KVM allows KVM_GUEST_MEMFD_ALLOW_HUGEPAGE for guest memfd. When the flag is set, KVM tries to allocate memory with transparent hugeapge at first and falls back to non-hugepage on failure. However, KVM defines one restriction that size must be hugepage size aligned when KVM_GUEST_MEMFD_ALLOW_HUGEPAGE is set. Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> --- v3: - New one in v3. --- system/physmem.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/system/physmem.c b/system/physmem.c index 0af2213cbd9c..c56b17e44df6 100644 --- a/system/physmem.c +++ b/system/physmem.c @@ -1803,6 +1803,40 @@ static void dirty_memory_extend(ram_addr_t old_ram_size, } }+#ifdef CONFIG_KVM+#define HPAGE_PMD_SIZE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size" +#define DEFAULT_PMD_SIZE (1ul << 21) + +static uint32_t get_thp_size(void) +{ + gchar *content = NULL; + const char *endptr; + static uint64_t thp_size = 0; + uint64_t tmp; + + if (thp_size != 0) { + return thp_size; + } + + 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 and fallback to something reasonable. */ + if (!tmp || !is_power_of_2(tmp)) { + warn_report("Read unsupported THP size: %" PRIx64, tmp); + } else { + thp_size = tmp; + } + } + + if (!thp_size) { + thp_size = DEFAULT_PMD_SIZE; + }
... did you shamelessly copy that from hw/virtio/virtio-mem.c ? ;) This should be factored out into a common helper. -- Cheers, David / dhildenb
