On 9/14/2023 11:50, Xiaoyao Li wrote:
> From: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
>
> Add KVM gmem support to RAMBlock so both normal hva based memory
> and kvm gmem fd based private memory can be associated in one RAMBlock.
>
> Introduce new flag RAM_KVM_GMEM. It calls KVM ioctl to create private
> gmem for the RAMBlock when it's set.
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
Kindly reminding the author's Signed-off-by is missing.
> ---
> accel/kvm/kvm-all.c | 17 +++++++++++++++++
> include/exec/memory.h | 3 +++
> include/exec/ramblock.h | 1 +
> include/sysemu/kvm.h | 2 ++
> softmmu/physmem.c | 18 +++++++++++++++---
> 5 files changed, 38 insertions(+), 3 deletions(-)
>
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 60aacd925393..185ae16d9620 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -4225,3 +4225,20 @@ void query_stats_schemas_cb(StatsSchemaList **result, Error **errp)
> query_stats_schema_vcpu(first_cpu, &stats_args);
> }
> }
> +
> +int kvm_create_guest_memfd(uint64_t size, uint64_t flags, Error **errp)
> +{
> + int fd;
> + struct kvm_create_guest_memfd gmem = {
> + .size = size,
> + /* TODO: to decide whether KVM_GUEST_MEMFD_ALLOW_HUGEPAGE is supported */
> + .flags = flags,
> + };
> +
> + fd = kvm_vm_ioctl(kvm_state, KVM_CREATE_GUEST_MEMFD, &gmem);
> + if (fd < 0) {
> + error_setg_errno(errp, errno, "%s: error creating kvm gmem\n", __func__);
> + }
> +
> + return fd;
> +}
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 68284428f87c..227cb2578e95 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -235,6 +235,9 @@ typedef struct IOMMUTLBEvent {
> /* RAM is an mmap-ed named file */
> #define RAM_NAMED_FILE (1 << 9)
>
> +/* RAM can be private that has kvm gmem backend */
> +#define RAM_KVM_GMEM (1 << 10)
> +
> static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
> IOMMUNotifierFlag flags,
> hwaddr start, hwaddr end,
> diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h
> index 69c6a5390293..0d158b3909c9 100644
> --- a/include/exec/ramblock.h
> +++ b/include/exec/ramblock.h
> @@ -41,6 +41,7 @@ struct RAMBlock {
> QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
> int fd;
> uint64_t fd_offset;
> + int gmem_fd;
> size_t page_size;
> /* dirty bitmap used during migration */
> unsigned long *bmap;
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 115f0cca79d1..f5b74c8dd8c5 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -580,4 +580,6 @@ bool kvm_arch_cpu_check_are_resettable(void);
> bool kvm_dirty_ring_enabled(void);
>
> uint32_t kvm_dirty_ring_size(void);
> +
> +int kvm_create_guest_memfd(uint64_t size, uint64_t flags, Error **errp);
> #endif
> diff --git a/softmmu/physmem.c b/softmmu/physmem.c
> index 3df73542e1fe..2d98a88f41f0 100644
> --- a/softmmu/physmem.c
> +++ b/softmmu/physmem.c
> @@ -1824,6 +1824,16 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
> }
> }
>
> + if (kvm_enabled() && new_block->flags & RAM_KVM_GMEM &&
> + new_block->gmem_fd < 0) {
> + new_block->gmem_fd = kvm_create_guest_memfd(new_block->max_length,
> + 0, errp);
> + if (new_block->gmem_fd < 0) {
> + qemu_mutex_unlock_ramlist();
> + return;
> + }
> + }
> +
> new_ram_size = MAX(old_ram_size,
> (new_block->offset + new_block->max_length) >> TARGET_PAGE_BITS);
> if (new_ram_size > old_ram_size) {
> @@ -1885,7 +1895,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
>
> /* Just support these ram flags by now. */
> assert((ram_flags & ~(RAM_SHARED | RAM_PMEM | RAM_NORESERVE |
> - RAM_PROTECTED | RAM_NAMED_FILE)) == 0);
> + RAM_PROTECTED | RAM_NAMED_FILE | RAM_KVM_GMEM)) == 0);
>
> if (xen_enabled()) {
> error_setg(errp, "-mem-path not supported with Xen");
> @@ -1920,6 +1930,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
> new_block->used_length = size;
> new_block->max_length = size;
> new_block->flags = ram_flags;
> + new_block->gmem_fd = -1;
> new_block->host = file_ram_alloc(new_block, size, fd, readonly,
> !file_size, offset, errp);
> if (!new_block->host) {
> @@ -1978,7 +1989,7 @@ RAMBlock *qemu_ram_alloc_internal(ram_addr_t size, ram_addr_t max_size,
> Error *local_err = NULL;
>
> assert((ram_flags & ~(RAM_SHARED | RAM_RESIZEABLE | RAM_PREALLOC |
> - RAM_NORESERVE)) == 0);
> + RAM_NORESERVE| RAM_KVM_GMEM)) == 0);
> assert(!host ^ (ram_flags & RAM_PREALLOC));
>
> size = HOST_PAGE_ALIGN(size);
> @@ -1990,6 +2001,7 @@ RAMBlock *qemu_ram_alloc_internal(ram_addr_t size, ram_addr_t max_size,
> new_block->max_length = max_size;
> assert(max_size >= size);
> new_block->fd = -1;
> + new_block->gmem_fd = -1;
> new_block->page_size = qemu_real_host_page_size();
> new_block->host = host;
> new_block->flags = ram_flags;
> @@ -2012,7 +2024,7 @@ RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
> RAMBlock *qemu_ram_alloc(ram_addr_t size, uint32_t ram_flags,
> MemoryRegion *mr, Error **errp)
> {
> - assert((ram_flags & ~(RAM_SHARED | RAM_NORESERVE)) == 0);
> + assert((ram_flags & ~(RAM_SHARED | RAM_NORESERVE | RAM_KVM_GMEM)) == 0);
> return qemu_ram_alloc_internal(size, size, NULL, NULL, ram_flags, mr, errp);
> }
>
