path: root/arch
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authorJordan Niethe <jniethe5@gmail.com>2019-10-04 12:53:17 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2019-10-09 17:16:59 +1100
commit7fe4e1176dfe47a243d8edd98d26abd11f91b042 (patch)
tree2197e9dd2ec96329b5607b5a67d980f2022eb921 /arch
parent5b216ea1c40cf06eead15054c70e238c9bd4729e (diff)
powerpc/kvm: Fix kvmppc_vcore->in_guest value in kvmhv_switch_to_host
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> Reviewed-by: Alistair Popple <alistair@popple.id.au> Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20191004025317.19340-1-jniethe5@gmail.com
Diffstat (limited to 'arch')
1 files changed, 1 insertions, 0 deletions
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
/* 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

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