Commit cc6929cc authored Dec 14, 2018 by Suraj Jitindar Singh Committed by Paul Mackerras Dec 17, 2018

KVM: PPC: Update kvmppc_st and kvmppc_ld to use quadrants



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>

parent dceadcf9

arch/powerpc/kvm/powerpc.c

+16 −2

Original line number	Diff line number	Diff line
		@@ -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)

Admin message