From: Jordan Niethe <jniethe5@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: aik@ozlabs.ru, alistair@popple.id.au,
patch-notifications@ellerman.id.au, kvm-ppc@vger.kernel.org,
Jordan Niethe <jniethe5@gmail.com>
Subject: [PATCH] powerpc/kvm: Fix kvmppc_vcore->in_guest value in kvmhv_switch_to_host
Date: Fri, 4 Oct 2019 12:53:17 +1000 [thread overview]
Message-ID: <20191004025317.19340-1-jniethe5@gmail.com> (raw)
kvmhv_switch_to_host() in arch/powerpc/kvm/book3s_hv_rmhandlers.S needs
to set kvmppc_vcore->in_guest to 0 to signal secondary CPUs to continue.
This happens after resetting the PCR. Before commit 13c7bb3c57dc
("powerpc/64s: Set reserved PCR bits"), r0 would always be 0 before it
was stored to kvmppc_vcore->in_guest. However because of this change in
the commit:
/* Reset PCR */
ld r0, VCORE_PCR(r5)
- cmpdi r0, 0
+ LOAD_REG_IMMEDIATE(r6, PCR_MASK)
+ cmpld r0, r6
beq 18f
- li r0, 0
- mtspr SPRN_PCR, r0
+ mtspr SPRN_PCR, r6
18:
/* Signal secondary CPUs to continue */
stb r0,VCORE_IN_GUEST(r5)
We are no longer comparing r0 against 0 and loading it with 0 if it
contains something else. Hence when we store r0 to
kvmppc_vcore->in_guest, it might not be 0. This means that secondary
CPUs will not be signalled to continue. Those CPUs get stuck and errors
like the following are logged:
KVM: CPU 1 seems to be stuck
KVM: CPU 2 seems to be stuck
KVM: CPU 3 seems to be stuck
KVM: CPU 4 seems to be stuck
KVM: CPU 5 seems to be stuck
KVM: CPU 6 seems to be stuck
KVM: CPU 7 seems to be stuck
This can be reproduced with:
$ for i in `seq 1 7` ; do chcpu -d $i ; done ;
$ taskset -c 0 qemu-system-ppc64 -smp 8,threads=8 \
-M pseries,accel=kvm,kvm-type=HV -m 1G -nographic -vga none \
-kernel vmlinux -initrd initrd.cpio.xz
Fix by making sure r0 is 0 before storing it to kvmppc_vcore->in_guest.
Fixes: 13c7bb3c57dc ("powerpc/64s: Set reserved PCR bits")
Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 74a9cfe84aee..faebcbb8c4db 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1921,6 +1921,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
mtspr SPRN_PCR, r6
18:
/* Signal secondary CPUs to continue */
+ li r0, 0
stb r0,VCORE_IN_GUEST(r5)
19: lis r8,0x7fff /* MAX_INT@h */
mtspr SPRN_HDEC,r8
--
2.20.1
WARNING: multiple messages have this Message-ID (diff)
From: Jordan Niethe <jniethe5@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: aik@ozlabs.ru, alistair@popple.id.au,
patch-notifications@ellerman.id.au, kvm-ppc@vger.kernel.org,
Jordan Niethe <jniethe5@gmail.com>
Subject: [PATCH] powerpc/kvm: Fix kvmppc_vcore->in_guest value in kvmhv_switch_to_host
Date: Fri, 04 Oct 2019 02:53:17 +0000 [thread overview]
Message-ID: <20191004025317.19340-1-jniethe5@gmail.com> (raw)
kvmhv_switch_to_host() in arch/powerpc/kvm/book3s_hv_rmhandlers.S needs
to set kvmppc_vcore->in_guest to 0 to signal secondary CPUs to continue.
This happens after resetting the PCR. Before commit 13c7bb3c57dc
("powerpc/64s: Set reserved PCR bits"), r0 would always be 0 before it
was stored to kvmppc_vcore->in_guest. However because of this change in
the commit:
/* Reset PCR */
ld r0, VCORE_PCR(r5)
- cmpdi r0, 0
+ LOAD_REG_IMMEDIATE(r6, PCR_MASK)
+ cmpld r0, r6
beq 18f
- li r0, 0
- mtspr SPRN_PCR, r0
+ mtspr SPRN_PCR, r6
18:
/* Signal secondary CPUs to continue */
stb r0,VCORE_IN_GUEST(r5)
We are no longer comparing r0 against 0 and loading it with 0 if it
contains something else. Hence when we store r0 to
kvmppc_vcore->in_guest, it might not be 0. This means that secondary
CPUs will not be signalled to continue. Those CPUs get stuck and errors
like the following are logged:
KVM: CPU 1 seems to be stuck
KVM: CPU 2 seems to be stuck
KVM: CPU 3 seems to be stuck
KVM: CPU 4 seems to be stuck
KVM: CPU 5 seems to be stuck
KVM: CPU 6 seems to be stuck
KVM: CPU 7 seems to be stuck
This can be reproduced with:
$ for i in `seq 1 7` ; do chcpu -d $i ; done ;
$ taskset -c 0 qemu-system-ppc64 -smp 8,threads=8 \
-M pseries,accel=kvm,kvm-type=HV -m 1G -nographic -vga none \
-kernel vmlinux -initrd initrd.cpio.xz
Fix by making sure r0 is 0 before storing it to kvmppc_vcore->in_guest.
Fixes: 13c7bb3c57dc ("powerpc/64s: Set reserved PCR bits")
Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
---
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 74a9cfe84aee..faebcbb8c4db 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1921,6 +1921,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
mtspr SPRN_PCR, r6
18:
/* Signal secondary CPUs to continue */
+ li r0, 0
stb r0,VCORE_IN_GUEST(r5)
19: lis r8,0x7fff /* MAX_INT@h */
mtspr SPRN_HDEC,r8
--
2.20.1
next reply other threads:[~2019-10-04 2:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-04 2:53 Jordan Niethe [this message]
2019-10-04 2:53 ` [PATCH] powerpc/kvm: Fix kvmppc_vcore->in_guest value in kvmhv_switch_to_host Jordan Niethe
2019-10-04 2:58 ` Alistair Popple
2019-10-04 2:58 ` Alistair Popple
2019-10-05 2:26 ` Alexey Kardashevskiy
2019-10-05 2:26 ` Alexey Kardashevskiy
2019-10-07 23:25 ` Alistair Popple
2019-10-07 23:25 ` Alistair Popple
2019-10-11 8:22 ` Michael Ellerman
2019-10-11 8:22 ` Michael Ellerman
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