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powerpc/fsl: Emulate SPRN_BUCSR register

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commit 98518c4d8728656db349f875fcbbc7c126d4c973 upstream.

In order to flush the branch predictor the guest kernel performs
writes to the BUCSR register which is hypervisor privilleged. However,
the branch predictor is flushed at each KVM entry, so the branch
predictor has been already flushed, so just return as soon as possible
to guest.

Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
[mpe: Tweak comment formatting]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Diana Craciun 2019-03-29 22:26:11 +11:00 committed by Greg Kroah-Hartman
parent 191adcc50e
commit d09c53d3ba
1 changed files with 7 additions and 0 deletions
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7
arch/powerpc/kvm/e500_emulate.c
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@ -277,6 +277,13 @@ int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong spr_va
vcpu->arch.pwrmgtcr0 = spr_val;
break;
case SPRN_BUCSR:
/*
* If we are here, it means that we have already flushed the
* branch predictor, so just return to guest.
*/
break;
/* extra exceptions */
#ifdef CONFIG_SPE_POSSIBLE
case SPRN_IVOR32: