Commit bbcc9c06 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Avi Kivity
Browse files

powerpc/kvm: Fix magic page vs. 32-bit RTAS on ppc64 



When the kernel calls into RTAS, it switches to 32-bit mode. The
magic page was is longer accessible in that case, causing the
patched instructions in the RTAS call wrapper to crash.

This fixes it by making available a 32-bit mapping of the magic
page in that case. This mapping is flushed whenever we switch
the kernel back to 64-bit mode.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
[agraf: add a check if the magic page is mapped]
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 966cd0f3

arch/powerpc/kvm/book3s.c

+3 −0
Original line number Diff line number Diff line
@@ -291,6 +291,9 @@ pfn_t kvmppc_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn) 
{

	ulong mp_pa = vcpu->arch.magic_page_pa;



	if (!(vcpu->arch.shared->msr & MSR_SF))

		mp_pa = (uint32_t)mp_pa;



	/* Magic page override */

	if (unlikely(mp_pa) &&

	    unlikely(((gfn << PAGE_SHIFT) & KVM_PAM) ==

arch/powerpc/kvm/book3s_pr.c

+18 −0
Original line number Diff line number Diff line
@@ -145,6 +145,21 @@ void kvmppc_set_msr(struct kvm_vcpu *vcpu, u64 msr) 
		}

	}



	/*

	 * When switching from 32 to 64-bit, we may have a stale 32-bit

	 * magic page around, we need to flush it. Typically 32-bit magic

	 * page will be instanciated when calling into RTAS. Note: We

	 * assume that such transition only happens while in kernel mode,

	 * ie, we never transition from user 32-bit to kernel 64-bit with

	 * a 32-bit magic page around.

	 */

	if (vcpu->arch.magic_page_pa &&

	    !(old_msr & MSR_PR) && !(old_msr & MSR_SF) && (msr & MSR_SF)) {

		/* going from RTAS to normal kernel code */

		kvmppc_mmu_pte_flush(vcpu, (uint32_t)vcpu->arch.magic_page_pa,

				     ~0xFFFUL);

	}



	/* Preload FPU if it's enabled */

	if (vcpu->arch.shared->msr & MSR_FP)

		kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP);
@@ -252,6 +267,9 @@ static int kvmppc_visible_gfn(struct kvm_vcpu *vcpu, gfn_t gfn) 
{

	ulong mp_pa = vcpu->arch.magic_page_pa;



	if (!(vcpu->arch.shared->msr & MSR_SF))

		mp_pa = (uint32_t)mp_pa;



	if (unlikely(mp_pa) &&

	    unlikely((mp_pa & KVM_PAM) >> PAGE_SHIFT == gfn)) {

		return 1;

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