qemu/accel
Tom Lendacky 4cdc489eb9 i386/kvm: Prefault memory on page state change
A page state change is typically followed by an access of the page(s) and
results in another VMEXIT in order to map the page into the nested page
table. Depending on the size of page state change request, this can
generate a number of additional VMEXITs. For example, under SNP, when
Linux is utilizing lazy memory acceptance, memory is typically accepted in
4M chunks. A page state change request is submitted to mark the pages as
private, followed by validation of the memory. Since the guest_memfd
currently only supports 4K pages, each page validation will result in
VMEXIT to map the page, resulting in 1024 additional exits.

When performing a page state change, invoke KVM_PRE_FAULT_MEMORY for the
size of the page state change in order to pre-map the pages and avoid the
additional VMEXITs. This helps speed up boot times.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/f5411c42340bd2f5c14972551edb4e959995e42b.1743193824.git.thomas.lendacky@amd.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-06-06 14:32:54 +02:00
..
hvf accel/hvf: Include missing 'hw/core/cpu.h' header 2025-05-08 14:22:12 +02:00
kvm i386/kvm: Prefault memory on page state change 2025-06-06 14:32:54 +02:00
qtest qom: Have class_init() take a const data argument 2025-04-25 17:00:41 +02:00
stubs system/hvf: Expose hvf_enabled() to common code 2025-05-08 14:22:12 +02:00
tcg * target/i386/kvm: Intel TDX support 2025-05-30 11:41:07 -04:00
xen qom: Have class_init() take a const data argument 2025-04-25 17:00:41 +02:00
accel-blocker.c include: Rename sysemu/ -> system/ 2024-12-20 17:44:56 +01:00
accel-common.c accel: Move target-agnostic code from accel-target.c -> accel-common.c 2025-04-25 17:09:58 +02:00
accel-internal.h accel: Include missing 'qemu/accel.h' header in accel-internal.h 2025-04-25 17:09:58 +02:00
accel-system.c accel: Implement accel_init_ops_interfaces() for both system/user mode 2025-04-25 17:09:58 +02:00
accel-target.c accel: Move target-agnostic code from accel-target.c -> accel-common.c 2025-04-25 17:09:58 +02:00
accel-user.c accel: Implement accel_init_ops_interfaces() for both system/user mode 2025-04-25 17:09:58 +02:00
dummy-cpus.c include: Rename sysemu/ -> system/ 2024-12-20 17:44:56 +01:00
Kconfig hw/xen: Link XenPVH with GPEX PCIe bridge 2025-03-04 14:45:34 +01:00
meson.build accel: Move target-agnostic code from accel-target.c -> accel-common.c 2025-04-25 17:09:58 +02:00