Re: [PATCH 6/7] kvm mmu: enabling 1GB pages by extending backing_sizefuntion

From: Avi Kivity
Date: Sun Mar 29 2009 - 07:52:16 EST


Joerg Roedel wrote:
This patch enables support for 1GB pages in KVM by implementing
the support in backing_size().

@@ -490,18 +492,30 @@ static enum kvm_page_size host_page_size(struct kvm *kvm, gfn_t gfn)
static enum kvm_page_size backing_size(struct kvm_vcpu *vcpu, gfn_t gfn)
{
struct kvm_memory_slot *slot;
-
- if (has_wrprotected_page(vcpu->kvm, gfn))
- return KVM_PAGE_SIZE_4k;
-
- if (host_page_size(vcpu->kvm, gfn) < KVM_PAGE_SIZE_2M)
- return KVM_PAGE_SIZE_4k;
+ enum kvm_page_size host_size, ret;
slot = gfn_to_memslot(vcpu->kvm, gfn);
if (slot && slot->dirty_bitmap)
return KVM_PAGE_SIZE_4k;
- return KVM_PAGE_SIZE_2M;
+ host_size = host_page_size(vcpu->kvm, gfn);
+
+ switch (host_size) {
+ case KVM_PAGE_SIZE_1G:
+ if (!has_wrprotected_largepage(vcpu->kvm, gfn)) {
+ ret = KVM_PAGE_SIZE_1G;
+ break;
+ }

What if there's a wrprotected_page in there?

+ case KVM_PAGE_SIZE_2M:
+ if (!has_wrprotected_page(vcpu->kvm, gfn)) {
+ ret = KVM_PAGE_SIZE_2M;
+ break;
+ }
+ default:
+ ret = KVM_PAGE_SIZE_4k;
+ }
+
+ return ret;
}
/*


--
error compiling committee.c: too many arguments to function

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