| Message ID | 20170717081426.ma6b2w37zuowbu7o@mwanda (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 17/07/2017 10:14, Dan Carpenter wrote: > kvm_read_cr3() returns an unsigned long and gfn is a u64. We intended > to mask out the bottom 5 bits but because of the type issue we mask the > top 32 bits as well. I don't know if this is a real problem, but it > causes static checker warnings. It's intended. The VM is running in 32-bit PAE mode, and Table 4-7 of the Intel manual says: Table 4-7. Use of CR3 with PAE Paging Bit Position(s) Contents 4:0 Ignored 31:5 Physical address of the 32-Byte aligned page-directory-pointer table used for linear-address translation 63:32 Ignored (these bits exist only on processors supporting the Intel-64 architecture) I'll queue a revert of this patch. Paolo > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index ca128a9c9cc4..476b7f4e0e1f 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -594,8 +594,8 @@ bool pdptrs_changed(struct kvm_vcpu *vcpu) > (unsigned long *)&vcpu->arch.regs_avail)) > return true; > > - gfn = (kvm_read_cr3(vcpu) & ~31u) >> PAGE_SHIFT; > - offset = (kvm_read_cr3(vcpu) & ~31u) & (PAGE_SIZE - 1); > + gfn = (kvm_read_cr3(vcpu) & ~31ul) >> PAGE_SHIFT; > + offset = (kvm_read_cr3(vcpu) & ~31ul) & (PAGE_SIZE - 1); > r = kvm_read_nested_guest_page(vcpu, gfn, pdpte, offset, sizeof(pdpte), > PFERR_USER_MASK | PFERR_WRITE_MASK); > if (r < 0) >
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ca128a9c9cc4..476b7f4e0e1f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -594,8 +594,8 @@ bool pdptrs_changed(struct kvm_vcpu *vcpu) (unsigned long *)&vcpu->arch.regs_avail)) return true; - gfn = (kvm_read_cr3(vcpu) & ~31u) >> PAGE_SHIFT; - offset = (kvm_read_cr3(vcpu) & ~31u) & (PAGE_SIZE - 1); + gfn = (kvm_read_cr3(vcpu) & ~31ul) >> PAGE_SHIFT; + offset = (kvm_read_cr3(vcpu) & ~31ul) & (PAGE_SIZE - 1); r = kvm_read_nested_guest_page(vcpu, gfn, pdpte, offset, sizeof(pdpte), PFERR_USER_MASK | PFERR_WRITE_MASK); if (r < 0)
kvm_read_cr3() returns an unsigned long and gfn is a u64. We intended to mask out the bottom 5 bits but because of the type issue we mask the top 32 bits as well. I don't know if this is a real problem, but it causes static checker warnings. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>