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KVM: PPC: Validate all tces before updating tables 

The KVM TCE handlers are written in a way so they fail when either
something went horribly wrong or the userspace did some obvious mistake
such as passing a misaligned address.

We are going to enhance the TCE checker to fail on attempts to map bigger
IOMMU page than the underlying pinned memory so let's valitate TCE
beforehand.

This should cause no behavioral change.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Alexey Kardashevskiy 2018-09-10 18:29:08 +10:00 committed by Michael Ellerman
parent b66081e25e
commit e199ad2bf5
2 changed files with 22 additions and 0 deletions
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18
arch/powerpc/kvm/book3s_64_vio.c
View File

@ -599,6 +599,24 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
ret = kvmppc_tce_validate(stt, tce);
if (ret != H_SUCCESS)
goto unlock_exit;
}
for (i = 0; i < npages; ++i) {
/*
* This looks unsafe, because we validate, then regrab
* the TCE from userspace which could have been changed by
* another thread.
*
* But it actually is safe, because the relevant checks will be
* re-executed in the following code. If userspace tries to
* change this dodgily it will result in a messier failure mode
* but won't threaten the host.
*/
if (get_user(tce, tces + i)) {
ret = H_TOO_HARD;
goto unlock_exit;
}
tce = be64_to_cpu(tce);
if (kvmppc_gpa_to_ua(vcpu->kvm,
tce & ~(TCE_PCI_READ | TCE_PCI_WRITE),

4
arch/powerpc/kvm/book3s_64_vio_hv.c
View File

@ -524,6 +524,10 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
ret = kvmppc_tce_validate(stt, tce);
if (ret != H_SUCCESS)
goto unlock_exit;
}
for (i = 0; i < npages; ++i) {
unsigned long tce = be64_to_cpu(((u64 *)tces)[i]);
ua = 0;
if (kvmppc_gpa_to_ua(vcpu->kvm,