Commit c820c2aa authored by Rusty Russell's avatar Rusty Russell Committed by Avi Kivity

KVM: load_pdptrs() cleanups

load_pdptrs can be handed an invalid cr3, and it should not oops.
This can happen because we injected #gp in set_cr3() after we set
vcpu->cr3 to the invalid value, or from kvm_vcpu_ioctl_set_sregs(), or
memory configuration changes after the guest did set_cr3().

We should also copy the pdpte array once, before checking and
assigning, otherwise an SMP guest can potentially alter the values
between the check and the set.

Finally one nitpick: ret = 1 should be done as late as possible: this
allows GCC to check for unset "ret" should the function change in
future.
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 3ccb8827
...@@ -442,30 +442,32 @@ static int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3) ...@@ -442,30 +442,32 @@ static int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)
gfn_t pdpt_gfn = cr3 >> PAGE_SHIFT; gfn_t pdpt_gfn = cr3 >> PAGE_SHIFT;
unsigned offset = ((cr3 & (PAGE_SIZE-1)) >> 5) << 2; unsigned offset = ((cr3 & (PAGE_SIZE-1)) >> 5) << 2;
int i; int i;
u64 pdpte;
u64 *pdpt; u64 *pdpt;
int ret; int ret;
struct page *page; struct page *page;
u64 pdpte[ARRAY_SIZE(vcpu->pdptrs)];
spin_lock(&vcpu->kvm->lock); spin_lock(&vcpu->kvm->lock);
page = gfn_to_page(vcpu->kvm, pdpt_gfn); page = gfn_to_page(vcpu->kvm, pdpt_gfn);
/* FIXME: !page - emulate? 0xff? */ if (!page) {
ret = 0;
goto out;
}
pdpt = kmap_atomic(page, KM_USER0); pdpt = kmap_atomic(page, KM_USER0);
memcpy(pdpte, pdpt+offset, sizeof(pdpte));
kunmap_atomic(pdpt, KM_USER0);
ret = 1; for (i = 0; i < ARRAY_SIZE(pdpte); ++i) {
for (i = 0; i < 4; ++i) { if ((pdpte[i] & 1) && (pdpte[i] & 0xfffffff0000001e6ull)) {
pdpte = pdpt[offset + i];
if ((pdpte & 1) && (pdpte & 0xfffffff0000001e6ull)) {
ret = 0; ret = 0;
goto out; goto out;
} }
} }
ret = 1;
for (i = 0; i < 4; ++i) memcpy(vcpu->pdptrs, pdpte, sizeof(vcpu->pdptrs));
vcpu->pdptrs[i] = pdpt[offset + i];
out: out:
kunmap_atomic(pdpt, KM_USER0);
spin_unlock(&vcpu->kvm->lock); spin_unlock(&vcpu->kvm->lock);
return ret; return ret;
......
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