Patch "powerpc/fsl: Emulate SPRN_BUCSR register" has been added to the 4.19-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    powerpc/fsl: Emulate SPRN_BUCSR register

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-fsl-emulate-sprn_bucsr-register.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From foo@baz Fri Mar 29 16:04:51 CET 2019
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Fri, 29 Mar 2019 22:26:11 +1100
Subject: powerpc/fsl: Emulate SPRN_BUCSR register
To: stable@vger.kernel.org, gregkh@linuxfoundation.org
Cc: linuxppc-dev@ozlabs.org, diana.craciun@nxp.com, msuchanek@suse.de, christophe.leroy@c-s.fr
Message-ID: <20190329112620.14489-24-mpe@ellerman.id.au>

From: Diana Craciun <diana.craciun@nxp.com>

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>
---
 arch/powerpc/kvm/e500_emulate.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/arch/powerpc/kvm/e500_emulate.c
+++ b/arch/powerpc/kvm/e500_emulate.c
@@ -277,6 +277,13 @@ int kvmppc_core_emulate_mtspr_e500(struc
 		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:


Patches currently in stable-queue which might be from mpe@ellerman.id.au are

queue-4.19/powerpc-fsl-emulate-sprn_bucsr-register.patch
queue-4.19/powerpc-fsl-flush-the-branch-predictor-at-each-kernel-entry-64bit.patch
queue-4.19/powerpc-fsl-update-spectre-v2-reporting.patch
queue-4.19/powerpc-fsl-add-macro-to-flush-the-branch-predictor.patch
queue-4.19/powerpc-security-fix-spectre_v2-reporting.patch
queue-4.19/powerpc-fsl-fix-the-flush-of-branch-predictor.patch
queue-4.19/powerpc-fsl-enable-runtime-patching-if-nospectre_v2-boot-arg-is-used.patch
queue-4.19/powerpc-fsl-fixed-warning-orphan-section-__btb_flush_fixup.patch
queue-4.19/powerpc-fsl-add-nospectre_v2-command-line-argument.patch
queue-4.19/powerpc-fsl-add-infrastructure-to-fixup-branch-predictor-flush.patch
queue-4.19/powerpc-fsl-flush-the-branch-predictor-at-each-kernel-entry-32-bit.patch
queue-4.19/powerpc-fsl-flush-branch-predictor-when-entering-kvm.patch