KVM: arm64: Assume write fault on S1PTW permission fault on instruction fetch
KVM currently assumes that an instruction abort can never be a write.
This is in general true, except when the abort is triggered by
a S1PTW on instruction fetch that tries to update the S1 page tables
(to set AF, for example).
This can happen if the page tables have been paged out and brought
back in without seeing a direct write to them (they are thus marked
read only), and the fault handling code will make the PT executable(!)
instead of writable. The guest gets stuck forever.
In these conditions, the permission fault must be considered as
a write so that the Stage-1 update can take place. This is essentially
the I-side equivalent of the problem fixed by 60e21a0ef54c ("arm64: KVM:
Take S1 walks into account when determining S2 write faults").
Update both kvm_is_write_fault() to return true on IABT+S1PTW, as well
as kvm_vcpu_trap_is_iabt() to return false in the same conditions.
Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
1 file changed
