From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
With 16K pagesize, the hugepage size is 32M. Align the guest
memory to the hugepagesize for 16K.
To query the host page size, we use sysconf(_SC_PAGESIZE) instead of
getpagesize, as suggested by man 2 getpagesize for portable applications.
Also use the sysconf function instead of getpagesize when setting
kvm->ram_pagesize.
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Andre Przywara <andre.przywara@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Tested-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
---
arm/kvm.c | 36 +++++++++++++++++++++++++++++-------
builtin-run.c | 4 ++--
util/util.c | 2 +-
3 files changed, 32 insertions(+), 10 deletions(-)
diff --git a/arm/kvm.c b/arm/kvm.c
index 1f85fc60588f..1c5bdb8026bf 100644
--- a/arm/kvm.c
+++ b/arm/kvm.c
@@ -59,14 +59,33 @@ void kvm__arch_set_cmdline(char *cmdline, bool video)
void kvm__arch_init(struct kvm *kvm, const char *hugetlbfs_path, u64 ram_size)
{
+ unsigned long alignment;
+
/*
- * Allocate guest memory. We must align our buffer to 64K to
- * correlate with the maximum guest page size for virtio-mmio.
- * If using THP, then our minimal alignment becomes 2M.
- * 2M trumps 64K, so let's go with that.
+ * Allocate guest memory. If the user wants to use hugetlbfs, then the
+ * specified guest memory size must be a multiple of the host huge page
+ * size in order for the allocation to succeed. The mmap return adress
+ * is naturally aligned to the huge page size, so in this case we don't
+ * need to perform any alignment.
+ *
+ * Otherwise, we must align our buffer to 64K to correlate with the
+ * maximum guest page size for virtio-mmio. If using THP, then our
+ * minimal alignment becomes 2M with a 4K page size. With a 16K page
+ * size, the alignment becomes 32M. 32M and 2M trump 64K, so let's go
+ * with the largest alignment supported by the host.
*/
+ if (hugetlbfs_path) {
+ /* Don't do any alignment. */
+ alignment = 0;
+ } else {
+ if (sysconf(_SC_PAGESIZE) == SZ_16K)
+ alignment = SZ_32M;
+ else
+ alignment = SZ_2M;
+ }
+
kvm->ram_size = min(ram_size, (u64)ARM_MAX_MEMORY(kvm));
- kvm->arch.ram_alloc_size = kvm->ram_size + SZ_2M;
+ kvm->arch.ram_alloc_size = kvm->ram_size + alignment;
kvm->arch.ram_alloc_start = mmap_anon_or_hugetlbfs(kvm, hugetlbfs_path,
kvm->arch.ram_alloc_size);
@@ -74,8 +93,11 @@ void kvm__arch_init(struct kvm *kvm, const char *hugetlbfs_path, u64 ram_size)
die("Failed to map %lld bytes for guest memory (%d)",
kvm->arch.ram_alloc_size, errno);
- kvm->ram_start = (void *)ALIGN((unsigned long)kvm->arch.ram_alloc_start,
- SZ_2M);
+ kvm->ram_start = kvm->arch.ram_alloc_start;
+ /* The result of aligning to 0 is 0. Let's avoid that. */
+ if (alignment)
+ kvm->ram_start = (void *)ALIGN((unsigned long)kvm->ram_start,
+ alignment);
madvise(kvm->arch.ram_alloc_start, kvm->arch.ram_alloc_size,
MADV_MERGEABLE);
diff --git a/builtin-run.c b/builtin-run.c
index f8dc6c7229b0..c867c8ba0892 100644
--- a/builtin-run.c
+++ b/builtin-run.c
@@ -127,8 +127,8 @@ void kvm_run_set_wrapper_sandbox(void)
"Run this script when booting into custom" \
" rootfs"), \
OPT_STRING('\0', "hugetlbfs", &(cfg)->hugetlbfs_path, "path", \
- "Hugetlbfs path"), \
- \
+ "Hugetlbfs path. Memory size must be a multiple"\
+ " of the huge page size"), \
OPT_GROUP("Kernel options:"), \
OPT_STRING('k', "kernel", &(cfg)->kernel_filename, "kernel", \
"Kernel to boot in virtual machine"), \
diff --git a/util/util.c b/util/util.c
index 1877105e3c08..217addd75e6f 100644
--- a/util/util.c
+++ b/util/util.c
@@ -127,7 +127,7 @@ void *mmap_anon_or_hugetlbfs(struct kvm *kvm, const char *hugetlbfs_path, u64 si
*/
return mmap_hugetlbfs(kvm, hugetlbfs_path, size);
else {
- kvm->ram_pagesize = getpagesize();
+ kvm->ram_pagesize = sysconf(_SC_PAGESIZE);
return mmap(NULL, size, PROT_RW, MAP_ANON_NORESERVE, -1, 0);
}
}
--
2.7.4
