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Add patch to fix SMT guests on POWER7 (rhbz 1227877)

This commit is contained in:
Josh Boyer 2015-06-04 07:32:27 -04:00
parent 436b9d9276
commit 045cecf6bb
2 changed files with 65 additions and 0 deletions
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7
kernel.spec
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@ -701,6 +701,9 @@ Patch26220: 0001-mwifiex-use-del_timer-variant-in-interrupt-context.patch
#rhbz 1226743
Patch26221: drm-i915-turn-off-wc-mmaps.patch
#rhbz 1227877
Patch26222: powerpc-powernv-Restore-non-volatile-CRs-after-nap.patch
# END OF PATCH DEFINITIONS
%endif
@ -1517,6 +1520,9 @@ ApplyPatch 0001-mwifiex-use-del_timer-variant-in-interrupt-context.patch
#rhbz 1226743
ApplyPatch drm-i915-turn-off-wc-mmaps.patch
#rhbz 1227877
ApplyPatch powerpc-powernv-Restore-non-volatile-CRs-after-nap.patch
# END OF PATCH APPLICATIONS
%endif
@ -2368,6 +2374,7 @@ fi
#
%changelog
* Thu Jun 04 2015 Josh Boyer <jwboyer@fedoraproject.org>
- Add patch to fix SMT guests on POWER7 (rhbz 1227877)
- Add patch to turn of WC mmaps on i915 from airlied (rhbz 1226743)
* Wed Jun 03 2015 Laura Abbott <labbott@fedoraproject.org>

58
powerpc-powernv-Restore-non-volatile-CRs-after-nap.patch Normal file
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@ -0,0 +1,58 @@
From: Sam Bobroff <sam.bobroff@au1.ibm.com>
Date: Fri, 1 May 2015 16:50:34 +1000
Subject: [PATCH] powerpc/powernv: Restore non-volatile CRs after nap
Patches 7cba160ad "powernv/cpuidle: Redesign idle states management"
and 77b54e9f2 "powernv/powerpc: Add winkle support for offline cpus"
use non-volatile condition registers (cr2, cr3 and cr4) early in the system
reset interrupt handler (system_reset_pSeries()) before it has been determined
if state loss has occurred. If state loss has not occurred, control returns via
the power7_wakeup_noloss() path which does not restore those condition
registers, leaving them corrupted.
Fix this by restoring the condition registers in the power7_wakeup_noloss()
case.
This is apparent when running a KVM guest on hardware that does not
support winkle or sleep and the guest makes use of secondary threads. In
practice this means Power7 machines, though some early unreleased Power8
machines may also be susceptible.
The secondary CPUs are taken off line before the guest is started and
they call pnv_smp_cpu_kill_self(). This checks support for sleep
states (in this case there is no support) and power7_nap() is called.
When the CPU is woken, power7_nap() returns and because the CPU is
still off line, the main while loop executes again. The sleep states
support test is executed again, but because the tested values cannot
have changed, the compiler has optimized the test away and instead we
rely on the result of the first test, which has been left in cr3
and/or cr4. With the result overwritten, the wrong branch is taken and
power7_winkle() is called on a CPU that does not support it, leading
to it stalling.
Fixes: 7cba160ad789 ("powernv/cpuidle: Redesign idle states management")
Fixes: 77b54e9f213f ("powernv/powerpc: Add winkle support for offline cpus")
[mpe: Massage change log a bit more]
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/kernel/idle_power7.S | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
index 05adc8bbdef8..401d8d0085aa 100644
--- a/arch/powerpc/kernel/idle_power7.S
+++ b/arch/powerpc/kernel/idle_power7.S
@@ -500,9 +500,11 @@ BEGIN_FTR_SECTION
CHECK_HMI_INTERRUPT
END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
ld r1,PACAR1(r13)
+ ld r6,_CCR(r1)
ld r4,_MSR(r1)
ld r5,_NIP(r1)
addi r1,r1,INT_FRAME_SIZE
+ mtcr r6
mtspr SPRN_SRR1,r4
mtspr SPRN_SRR0,r5
rfid