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KVM: cleanup and add shortcuts to kvm_range_has_memory_attributes()

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Use a guard to simplify early returns, and add two more easy
shortcuts.  If the requested attributes are invalid, the attributes
xarray will never show them as set.  And if testing a single page,
kvm_get_memory_attributes() is more efficient.

Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2024-07-11 18:27:53 -04:00
parent de80252414
commit e300614f10
1 changed files with 20 additions and 22 deletions
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42
virt/kvm/kvm_main.c
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@ -2398,6 +2398,14 @@ static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm,
#endif /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
#ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES
static u64 kvm_supported_mem_attributes(struct kvm *kvm)
{
if (!kvm || kvm_arch_has_private_mem(kvm))
return KVM_MEMORY_ATTRIBUTE_PRIVATE;
return 0;
}
/*
* Returns true if _all_ gfns in the range [@start, @end) have attributes
* matching @attrs.
@ -2406,40 +2414,30 @@ bool kvm_range_has_memory_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
unsigned long attrs)
{
XA_STATE(xas, &kvm->mem_attr_array, start);
unsigned long mask = kvm_supported_mem_attributes(kvm);
unsigned long index;
bool has_attrs;
void *entry;
rcu_read_lock();
if (attrs & ~mask)
return false;
if (!attrs) {
has_attrs = !xas_find(&xas, end - 1);
goto out;
}
if (end == start + 1)
return kvm_get_memory_attributes(kvm, start) == attrs;
guard(rcu)();
if (!attrs)
return !xas_find(&xas, end - 1);
has_attrs = true;
for (index = start; index < end; index++) {
do {
entry = xas_next(&xas);
} while (xas_retry(&xas, entry));
if (xas.xa_index != index || xa_to_value(entry) != attrs) {
has_attrs = false;
break;
}
if (xas.xa_index != index || xa_to_value(entry) != attrs)
return false;
}
out:
rcu_read_unlock();
return has_attrs;
}
static u64 kvm_supported_mem_attributes(struct kvm *kvm)
{
if (!kvm || kvm_arch_has_private_mem(kvm))
return KVM_MEMORY_ATTRIBUTE_PRIVATE;
return 0;
return true;
}
static __always_inline void kvm_handle_gfn_range(struct kvm *kvm,