On 12/12/2023 9:56 PM, Wang, Wei W wrote:
On Wednesday, November 15, 2023 3:14 PM, Xiaoyao Li wrote:
Introduce the helper functions to set the attributes of a range of memory to
private or shared.
This is necessary to notify KVM the private/shared attribute of each gpa range.
KVM needs the information to decide the GPA needs to be mapped at hva-
based shared memory or guest_memfd based private memory.
Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
---
accel/kvm/kvm-all.c | 42 ++++++++++++++++++++++++++++++++++++++++++
include/sysemu/kvm.h | 3 +++
2 files changed, 45 insertions(+)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index
69afeb47c9c0..76e2404d54d2 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -102,6 +102,7 @@ bool kvm_has_guest_debug; static int kvm_sstep_flags;
static bool kvm_immediate_exit; static bool kvm_guest_memfd_supported;
+static uint64_t kvm_supported_memory_attributes;
static hwaddr kvm_max_slot_size = ~0;
static const KVMCapabilityInfo kvm_required_capabilites[] = { @@ -1305,6
+1306,44 @@ void kvm_set_max_memslot_size(hwaddr max_slot_size)
kvm_max_slot_size = max_slot_size;
}
+static int kvm_set_memory_attributes(hwaddr start, hwaddr size,
+uint64_t attr) {
+ struct kvm_memory_attributes attrs;
+ int r;
+
+ attrs.attributes = attr;
+ attrs.address = start;
+ attrs.size = size;
+ attrs.flags = 0;
+
+ r = kvm_vm_ioctl(kvm_state, KVM_SET_MEMORY_ATTRIBUTES, &attrs);
+ if (r) {
+ warn_report("%s: failed to set memory (0x%lx+%#zx) with attr 0x%lx
error '%s'",
+ __func__, start, size, attr, strerror(errno));
+ }
+ return r;
+}
+
+int kvm_set_memory_attributes_private(hwaddr start, hwaddr size) {
+ if (!(kvm_supported_memory_attributes &
KVM_MEMORY_ATTRIBUTE_PRIVATE)) {
+ error_report("KVM doesn't support PRIVATE memory attribute\n");
+ return -EINVAL;
+ }
+
+ return kvm_set_memory_attributes(start, size,
+KVM_MEMORY_ATTRIBUTE_PRIVATE); }
+
+int kvm_set_memory_attributes_shared(hwaddr start, hwaddr size) {
+ if (!(kvm_supported_memory_attributes &
KVM_MEMORY_ATTRIBUTE_PRIVATE)) {
+ error_report("KVM doesn't support PRIVATE memory attribute\n");
+ return -EINVAL;
+ }
Duplicate code in kvm_set_memory_attributes_shared/private.
Why not move the check into kvm_set_memory_attributes?
Because it's not easy to put the check into there.
Both setting and clearing one bit require the capability check. If
moving the check into kvm_set_memory_attributes(), the check of
KVM_MEMORY_ATTRIBUTE_PRIVATE will have to become unconditionally, which
is not aligned to the function name because the name is not restricted
to shared/private attribute only.
