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KVM: PPC: Update kvmppc_st and kvmppc_ld to use quadrants

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The functions kvmppc_st and kvmppc_ld are used to access guest memory
from the host using a guest effective address. They do so by translating
through the process table to obtain a guest real address and then using
kvm_read_guest or kvm_write_guest to make the access with the guest real
address.

This method of access however only works for L1 guests and will give the
incorrect results for a nested guest.

We can however use the store_to_eaddr and load_from_eaddr kvmppc_ops to
perform the access for a nested guesti (and a L1 guest). So attempt this
method first and fall back to the old method if this fails and we aren't
running a nested guest.

At this stage there is no fall back method to perform the access for a
nested guest and this is left as a future improvement. For now we will
return to the nested guest and rely on the fact that a translation
should be faulted in before retrying the access.

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Suraj Jitindar Singh 2018-12-14 16:29:07 +11:00 committed by Paul Mackerras
parent dceadcf91b
commit cc6929cc84
1 changed files with 16 additions and 2 deletions
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18
arch/powerpc/kvm/powerpc.c
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@ -331,10 +331,17 @@ int kvmppc_st(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr,
{
ulong mp_pa = vcpu->arch.magic_page_pa & KVM_PAM & PAGE_MASK;
struct kvmppc_pte pte;
int r;
int r = -EINVAL;
vcpu->stat.st++;
if (vcpu->kvm->arch.kvm_ops && vcpu->kvm->arch.kvm_ops->store_to_eaddr)
r = vcpu->kvm->arch.kvm_ops->store_to_eaddr(vcpu, eaddr, ptr,
size);
if ((!r) || (r == -EAGAIN))
return r;
r = kvmppc_xlate(vcpu, *eaddr, data ? XLATE_DATA : XLATE_INST,
XLATE_WRITE, &pte);
if (r < 0)
@ -367,10 +374,17 @@ int kvmppc_ld(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr,
{
ulong mp_pa = vcpu->arch.magic_page_pa & KVM_PAM & PAGE_MASK;
struct kvmppc_pte pte;
int rc;
int rc = -EINVAL;
vcpu->stat.ld++;
if (vcpu->kvm->arch.kvm_ops && vcpu->kvm->arch.kvm_ops->load_from_eaddr)
rc = vcpu->kvm->arch.kvm_ops->load_from_eaddr(vcpu, eaddr, ptr,
size);
if ((!rc) || (rc == -EAGAIN))
return rc;
rc = kvmppc_xlate(vcpu, *eaddr, data ? XLATE_DATA : XLATE_INST,
XLATE_READ, &pte);
if (rc)