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KVM: x86/mmu: Add a helper to consolidate root sp allocation
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Add a helper, mmu_alloc_root(), to consolidate the allocation of a root
shadow page, which has the same basic mechanics for all flavors of TDP
and shadow paging.

Note, __pa(sp->spt) doesn't need to be protected by mmu_lock, sp->spt
points at a kernel page.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200428023714.31923-1-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Sean Christopherson authored and Paolo Bonzini committed May 15, 2020
1 parent 3bae045 commit 8123f26
Showing 1 changed file with 39 additions and 49 deletions.
88 changes: 39 additions & 49 deletions arch/x86/kvm/mmu/mmu.c
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Original file line number Diff line number Diff line change
@@ -3678,37 +3678,43 @@ static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn)
return ret;
}

static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva,
u8 level, bool direct)
{
struct kvm_mmu_page *sp;

spin_lock(&vcpu->kvm->mmu_lock);

if (make_mmu_pages_available(vcpu)) {
spin_unlock(&vcpu->kvm->mmu_lock);
return INVALID_PAGE;
}
sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL);
++sp->root_count;

spin_unlock(&vcpu->kvm->mmu_lock);
return __pa(sp->spt);
}

static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
{
u8 shadow_root_level = vcpu->arch.mmu->shadow_root_level;
hpa_t root;
unsigned i;

if (vcpu->arch.mmu->shadow_root_level >= PT64_ROOT_4LEVEL) {
spin_lock(&vcpu->kvm->mmu_lock);
if(make_mmu_pages_available(vcpu) < 0) {
spin_unlock(&vcpu->kvm->mmu_lock);
if (shadow_root_level >= PT64_ROOT_4LEVEL) {
root = mmu_alloc_root(vcpu, 0, 0, shadow_root_level, true);
if (!VALID_PAGE(root))
return -ENOSPC;
}
sp = kvm_mmu_get_page(vcpu, 0, 0,
vcpu->arch.mmu->shadow_root_level, 1, ACC_ALL);
++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) {
vcpu->arch.mmu->root_hpa = root;
} else if (shadow_root_level == PT32E_ROOT_LEVEL) {
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->arch.mmu->pae_root[i];
MMU_WARN_ON(VALID_PAGE(vcpu->arch.mmu->pae_root[i]));

MMU_WARN_ON(VALID_PAGE(root));
spin_lock(&vcpu->kvm->mmu_lock);
if (make_mmu_pages_available(vcpu) < 0) {
spin_unlock(&vcpu->kvm->mmu_lock);
root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT),
i << 30, PT32_ROOT_LEVEL, true);
if (!VALID_PAGE(root))
return -ENOSPC;
}
sp = kvm_mmu_get_page(vcpu, i << (30 - PAGE_SHIFT),
i << 30, PT32_ROOT_LEVEL, 1, ACC_ALL);
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);
@@ -3723,9 +3729,9 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)

static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
{
struct kvm_mmu_page *sp;
u64 pdptr, pm_mask;
gfn_t root_gfn, root_pgd;
hpa_t root;
int i;

root_pgd = vcpu->arch.mmu->get_guest_pgd(vcpu);
@@ -3739,20 +3745,12 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
* write-protect the guests page table root.
*/
if (vcpu->arch.mmu->root_level >= PT64_ROOT_4LEVEL) {
hpa_t root = vcpu->arch.mmu->root_hpa;
MMU_WARN_ON(VALID_PAGE(vcpu->arch.mmu->root_hpa));

MMU_WARN_ON(VALID_PAGE(root));

spin_lock(&vcpu->kvm->mmu_lock);
if (make_mmu_pages_available(vcpu) < 0) {
spin_unlock(&vcpu->kvm->mmu_lock);
root = mmu_alloc_root(vcpu, root_gfn, 0,
vcpu->arch.mmu->shadow_root_level, false);
if (!VALID_PAGE(root))
return -ENOSPC;
}
sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
vcpu->arch.mmu->shadow_root_level, 0, ACC_ALL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu->root_hpa = root;
goto set_root_pgd;
}
@@ -3767,9 +3765,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK;

for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->arch.mmu->pae_root[i];

MMU_WARN_ON(VALID_PAGE(root));
MMU_WARN_ON(VALID_PAGE(vcpu->arch.mmu->pae_root[i]));
if (vcpu->arch.mmu->root_level == PT32E_ROOT_LEVEL) {
pdptr = vcpu->arch.mmu->get_pdptr(vcpu, i);
if (!(pdptr & PT_PRESENT_MASK)) {
@@ -3780,17 +3776,11 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
if (mmu_check_root(vcpu, root_gfn))
return 1;
}
spin_lock(&vcpu->kvm->mmu_lock);
if (make_mmu_pages_available(vcpu) < 0) {
spin_unlock(&vcpu->kvm->mmu_lock);
return -ENOSPC;
}
sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30, PT32_ROOT_LEVEL,
0, ACC_ALL);
root = __pa(sp->spt);
++sp->root_count;
spin_unlock(&vcpu->kvm->mmu_lock);

root = mmu_alloc_root(vcpu, root_gfn, i << 30,
PT32_ROOT_LEVEL, false);
if (!VALID_PAGE(root))
return -ENOSPC;
vcpu->arch.mmu->pae_root[i] = root | pm_mask;
}
vcpu->arch.mmu->root_hpa = __pa(vcpu->arch.mmu->pae_root);

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