| Message ID | 20191004025317.19340-1-jniethe5@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 7fe4e1176dfe47a243d8edd98d26abd11f91b042 |
| Headers | show |
| Series | powerpc/kvm: Fix kvmppc_vcore->in_guest value in kvmhv_switch_to_host | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch next (6edfc6487b474fe01857dc3f1a9cd701bb9b21c8) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 7 lines checked |
Reviewed-by: Alistair Popple <alistair@popple.id.au> On Friday, 4 October 2019 12:53:17 PM AEST Jordan Niethe wrote: > 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 >
On 04/10/2019 12:53, Jordan Niethe wrote: > 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> Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru> > --- > 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 >
On Friday, 4 October 2019 12:53:17 PM AEDT Jordan Niethe wrote: > 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) Easy to understand how that was missed :-) Reviewed-by: Alistair Popple <alistair@popple.id.au> > 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 >
On Fri, 2019-10-04 at 02:53:17 UTC, Jordan Niethe wrote: > 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> Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/7fe4e1176dfe47a243d8edd98d26abd11f91b042 cheers
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
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(+)