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KVM: MMU: Refactor mmu_alloc_roots function

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This patch factors out the direct-mapping paths of the
mmu_alloc_roots function into a seperate function. This
makes it a lot easier to avoid all the unnecessary checks
done in the shadow path which may break when running direct.
In fact, this patch already fixes a problem when running PAE
guests on a PAE shadow page table.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Joerg Roedel 2010-09-10 17:30:59 +02:00 committed by Avi Kivity
parent d41d1895eb
commit 651dd37a9c
1 changed files with 60 additions and 22 deletions
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82
arch/x86/kvm/mmu.c
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@ -2357,42 +2357,77 @@ static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn)
return ret;
}
static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
{
struct kvm_mmu_page *sp;
int i;
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) {
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
sp = kvm_mmu_get_page(vcpu, 0, 0, PT64_ROOT_LEVEL,
1, ACC_ALL, NULL);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = __pa(sp->spt);
} else if (vcpu->arch.mmu.shadow_root_level == PT32E_ROOT_LEVEL) {
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->arch.mmu.pae_root[i];
ASSERT(!VALID_PAGE(root));
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
sp = kvm_mmu_get_page(vcpu, i << 30, i << 30,
PT32_ROOT_LEVEL, 1, ACC_ALL,
NULL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.pae_root[i] = root | PT_PRESENT_MASK;
vcpu->arch.mmu.root_hpa = __pa(vcpu->arch.mmu.pae_root);
}
} else
BUG();
return 0;
}
static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
{
int i;
gfn_t root_gfn;
struct kvm_mmu_page *sp;
int direct = 0;
u64 pdptr;
root_gfn = vcpu->arch.mmu.get_cr3(vcpu) >> PAGE_SHIFT;
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) {
if (mmu_check_root(vcpu, root_gfn))
return 1;
/*
* Do we shadow a long mode page table? If so we need to
* write-protect the guests page table root.
*/
if (vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;
ASSERT(!VALID_PAGE(root));
if (mmu_check_root(vcpu, root_gfn))
return 1;
if (vcpu->arch.mmu.direct_map) {
direct = 1;
root_gfn = 0;
}
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
PT64_ROOT_LEVEL, direct,
ACC_ALL, NULL);
sp = kvm_mmu_get_page(vcpu, root_gfn, 0, PT64_ROOT_LEVEL,
0, ACC_ALL, NULL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = root;
return 0;
}
direct = !is_paging(vcpu);
if (mmu_check_root(vcpu, root_gfn))
return 1;
/*
* We shadow a 32 bit page table. This may be a legacy 2-level
* or a PAE 3-level page table.
*/
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->arch.mmu.pae_root[i];
@ -2406,16 +2441,11 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
root_gfn = pdptr >> PAGE_SHIFT;
if (mmu_check_root(vcpu, root_gfn))
return 1;
} else if (vcpu->arch.mmu.root_level == 0)
root_gfn = 0;
if (vcpu->arch.mmu.direct_map) {
direct = 1;
root_gfn = i << 30;
}
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
PT32_ROOT_LEVEL, direct,
PT32_ROOT_LEVEL, 0,
ACC_ALL, NULL);
root = __pa(sp->spt);
++sp->root_count;
@ -2427,6 +2457,14 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
return 0;
}
static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
{
if (vcpu->arch.mmu.direct_map)
return mmu_alloc_direct_roots(vcpu);
else
return mmu_alloc_shadow_roots(vcpu);
}
static void mmu_sync_roots(struct kvm_vcpu *vcpu)
{
int i;