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RAMBlock: Add support of KVM private guest memfd

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Add KVM guest_memfd support to RAMBlock so both normal hva based memory
and kvm guest memfd based private memory can be associated in one RAMBlock.

Introduce new flag RAM_GUEST_MEMFD. When it's set, it calls KVM ioctl to
create private guest_memfd during RAMBlock setup.

Allocating a new RAM_GUEST_MEMFD flag to instruct the setup of guest memfd
is more flexible and extensible than simply relying on the VM type because
in the future we may have the case that not all the memory of a VM need
guest memfd. As a benefit, it also avoid getting MachineState in memory
subsystem.

Note, RAM_GUEST_MEMFD is supposed to be set for memory backends of
confidential guests, such as TDX VM. How and when to set it for memory
backends will be implemented in the following patches.

Introduce memory_region_has_guest_memfd() to query if the MemoryRegion has
KVM guest_memfd allocated.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-ID: <20240320083945.991426-7-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Xiaoyao Li 2024-03-20 03:39:02 -05:00 • committed by Paolo Bonzini
parent 0811baed49
commit 15f7a80c49
8 changed files with 90 additions and 7 deletions
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20
include/exec/memory.h
View file

@ -243,6 +243,9 @@ typedef struct IOMMUTLBEvent {
/* RAM FD is opened read-only */
#define RAM_READONLY_FD (1 << 11)
/* RAM can be private that has kvm guest memfd backend */
#define RAM_GUEST_MEMFD (1 << 12)
static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
IOMMUNotifierFlag flags,
hwaddr start, hwaddr end,
@ -1307,7 +1310,8 @@ bool memory_region_init_ram_nomigrate(MemoryRegion *mr,
* @name: Region name, becomes part of RAMBlock name used in migration stream
* must be unique within any device
* @size: size of the region.
* @ram_flags: RamBlock flags. Supported flags: RAM_SHARED, RAM_NORESERVE.
* @ram_flags: RamBlock flags. Supported flags: RAM_SHARED, RAM_NORESERVE,
* RAM_GUEST_MEMFD.
* @errp: pointer to Error*, to store an error if it happens.
*
* Note that this function does not do anything to cause the data in the
@ -1369,7 +1373,7 @@ bool memory_region_init_resizeable_ram(MemoryRegion *mr,
* (getpagesize()) will be used.
* @ram_flags: RamBlock flags. Supported flags: RAM_SHARED, RAM_PMEM,
* RAM_NORESERVE, RAM_PROTECTED, RAM_NAMED_FILE, RAM_READONLY,
* RAM_READONLY_FD
* RAM_READONLY_FD, RAM_GUEST_MEMFD
* @path: the path in which to allocate the RAM.
* @offset: offset within the file referenced by path
* @errp: pointer to Error*, to store an error if it happens.
@ -1399,7 +1403,7 @@ bool memory_region_init_ram_from_file(MemoryRegion *mr,
* @size: size of the region.
* @ram_flags: RamBlock flags. Supported flags: RAM_SHARED, RAM_PMEM,
* RAM_NORESERVE, RAM_PROTECTED, RAM_NAMED_FILE, RAM_READONLY,
* RAM_READONLY_FD
* RAM_READONLY_FD, RAM_GUEST_MEMFD
* @fd: the fd to mmap.
* @offset: offset within the file referenced by fd
* @errp: pointer to Error*, to store an error if it happens.
@ -1722,6 +1726,16 @@ static inline bool memory_region_is_romd(MemoryRegion *mr)
*/
bool memory_region_is_protected(MemoryRegion *mr);
/**
* memory_region_has_guest_memfd: check whether a memory region has guest_memfd
* associated
*
* Returns %true if a memory region's ram_block has valid guest_memfd assigned.
*
* @mr: the memory region being queried
*/
bool memory_region_has_guest_memfd(MemoryRegion *mr);
/**
* memory_region_get_iommu: check whether a memory region is an iommu
*