KVM: PPC: Interpret SDR1 as HVA in PAPR mode

When running a PAPR guest, the guest is not allowed to set SDR1 - instead
the HTAB information is held in internal hypervisor structures. But all of
our current code relies on SDR1 and walking the HTAB like on real hardware.

So in order to not be too intrusive, we simply set SDR1 to the HTAB we hold
in host memory. That way we can keep the HTAB in user space, but use it from
kernel space to map the guest.

Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/arch/powerpc/kvm/book3s_64_mmu.c b/arch/powerpc/kvm/book3s_64_mmu.c
index c6d3e194b6b4c2d42a4904c0d887e387cc0a50a7..b871721c0050e8e3f04353f80c925f63c89afded 100644 (file)
--- a/arch/powerpc/kvm/book3s_64_mmu.c
+++ b/arch/powerpc/kvm/book3s_64_mmu.c
@@ -128,7 +128,13 @@ static hva_t kvmppc_mmu_book3s_64_get_pteg(
        dprintk("MMU: page=0x%x sdr1=0x%llx pteg=0x%llx vsid=0x%llx\n",
                page, vcpu_book3s->sdr1, pteg, slbe->vsid);
 
-       r = gfn_to_hva(vcpu_book3s->vcpu.kvm, pteg >> PAGE_SHIFT);
+       /* When running a PAPR guest, SDR1 contains a HVA address instead
+           of a GPA */
+       if (vcpu_book3s->vcpu.arch.papr_enabled)
+               r = pteg;
+       else
+               r = gfn_to_hva(vcpu_book3s->vcpu.kvm, pteg >> PAGE_SHIFT);
+
        if (kvm_is_error_hva(r))
                return r;
        return r | (pteg & ~PAGE_MASK);