* arch/powerpc/kvm/powerpc.c:1141:7: warning: Redundant assignment of 'gpr' to itself. [selfAssignment]
@ 2021-06-25 14:07 kernel test robot
2021-06-26 10:28 ` Michael Ellerman
0 siblings, 1 reply; 2+ messages in thread
From: kernel test robot @ 2021-06-25 14:07 UTC (permalink / raw)
To: Cédric Le Goater; +Cc: kbuild-all, linux-kernel, Michael Ellerman
Hi Cédric,
First bad commit (maybe != root cause):
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 44db63d1ad8d71c6932cbe007eb41f31c434d140
commit: 9236f57a9e51c72ce426ccd2e53e123de7196a0f KVM: PPC: Make the VMX instruction emulation routines static
date: 5 months ago
compiler: powerpc64-linux-gcc (GCC) 9.3.0
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
cppcheck warnings: (new ones prefixed by >>)
>> arch/powerpc/kvm/powerpc.c:1141:7: warning: Redundant assignment of 'gpr' to itself. [selfAssignment]
gpr = sp_to_dp(gpr);
^
>> arch/powerpc/kvm/powerpc.c:1341:7: warning: Redundant assignment of 'val' to itself. [selfAssignment]
val = dp_to_sp(val);
^
vim +/gpr +1141 arch/powerpc/kvm/powerpc.c
6f63e81bda98cb Bin Lu 2017-02-21 1112
8c99d34578628b Tianjia Zhang 2020-04-27 1113 static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu)
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1114 {
8c99d34578628b Tianjia Zhang 2020-04-27 1115 struct kvm_run *run = vcpu->run;
3f649ab728cda8 Kees Cook 2020-06-03 1116 u64 gpr;
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1117
8e5b26b55a8b6a Alexander Graf 2010-01-08 1118 if (run->mmio.len > sizeof(gpr)) {
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1119 printk(KERN_ERR "bad MMIO length: %d\n", run->mmio.len);
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1120 return;
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1121 }
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1122
d078eed35de386 David Gibson 2015-02-03 1123 if (!vcpu->arch.mmio_host_swabbed) {
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1124 switch (run->mmio.len) {
b104d06632d089 Alexander Graf 2010-02-19 1125 case 8: gpr = *(u64 *)run->mmio.data; break;
8e5b26b55a8b6a Alexander Graf 2010-01-08 1126 case 4: gpr = *(u32 *)run->mmio.data; break;
8e5b26b55a8b6a Alexander Graf 2010-01-08 1127 case 2: gpr = *(u16 *)run->mmio.data; break;
8e5b26b55a8b6a Alexander Graf 2010-01-08 1128 case 1: gpr = *(u8 *)run->mmio.data; break;
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1129 }
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1130 } else {
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1131 switch (run->mmio.len) {
d078eed35de386 David Gibson 2015-02-03 1132 case 8: gpr = swab64(*(u64 *)run->mmio.data); break;
d078eed35de386 David Gibson 2015-02-03 1133 case 4: gpr = swab32(*(u32 *)run->mmio.data); break;
d078eed35de386 David Gibson 2015-02-03 1134 case 2: gpr = swab16(*(u16 *)run->mmio.data); break;
8e5b26b55a8b6a Alexander Graf 2010-01-08 1135 case 1: gpr = *(u8 *)run->mmio.data; break;
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1136 }
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1137 }
8e5b26b55a8b6a Alexander Graf 2010-01-08 1138
6f63e81bda98cb Bin Lu 2017-02-21 1139 /* conversion between single and double precision */
6f63e81bda98cb Bin Lu 2017-02-21 1140 if ((vcpu->arch.mmio_sp64_extend) && (run->mmio.len == 4))
6f63e81bda98cb Bin Lu 2017-02-21 @1141 gpr = sp_to_dp(gpr);
6f63e81bda98cb Bin Lu 2017-02-21 1142
3587d5348ced08 Alexander Graf 2010-02-19 1143 if (vcpu->arch.mmio_sign_extend) {
3587d5348ced08 Alexander Graf 2010-02-19 1144 switch (run->mmio.len) {
3587d5348ced08 Alexander Graf 2010-02-19 1145 #ifdef CONFIG_PPC64
3587d5348ced08 Alexander Graf 2010-02-19 1146 case 4:
3587d5348ced08 Alexander Graf 2010-02-19 1147 gpr = (s64)(s32)gpr;
3587d5348ced08 Alexander Graf 2010-02-19 1148 break;
3587d5348ced08 Alexander Graf 2010-02-19 1149 #endif
3587d5348ced08 Alexander Graf 2010-02-19 1150 case 2:
3587d5348ced08 Alexander Graf 2010-02-19 1151 gpr = (s64)(s16)gpr;
3587d5348ced08 Alexander Graf 2010-02-19 1152 break;
3587d5348ced08 Alexander Graf 2010-02-19 1153 case 1:
3587d5348ced08 Alexander Graf 2010-02-19 1154 gpr = (s64)(s8)gpr;
3587d5348ced08 Alexander Graf 2010-02-19 1155 break;
3587d5348ced08 Alexander Graf 2010-02-19 1156 }
3587d5348ced08 Alexander Graf 2010-02-19 1157 }
3587d5348ced08 Alexander Graf 2010-02-19 1158
b3c5d3c2a49602 Alexander Graf 2012-01-07 1159 switch (vcpu->arch.io_gpr & KVM_MMIO_REG_EXT_MASK) {
b3c5d3c2a49602 Alexander Graf 2012-01-07 1160 case KVM_MMIO_REG_GPR:
b104d06632d089 Alexander Graf 2010-02-19 1161 kvmppc_set_gpr(vcpu, vcpu->arch.io_gpr, gpr);
b104d06632d089 Alexander Graf 2010-02-19 1162 break;
b3c5d3c2a49602 Alexander Graf 2012-01-07 1163 case KVM_MMIO_REG_FPR:
2e6baa46b4ae78 Simon Guo 2018-05-21 1164 if (vcpu->kvm->arch.kvm_ops->giveup_ext)
2e6baa46b4ae78 Simon Guo 2018-05-21 1165 vcpu->kvm->arch.kvm_ops->giveup_ext(vcpu, MSR_FP);
2e6baa46b4ae78 Simon Guo 2018-05-21 1166
efff19122315f1 Paul Mackerras 2013-10-15 1167 VCPU_FPR(vcpu, vcpu->arch.io_gpr & KVM_MMIO_REG_MASK) = gpr;
b104d06632d089 Alexander Graf 2010-02-19 1168 break;
287d5611fab5a4 Alexander Graf 2010-04-01 1169 #ifdef CONFIG_PPC_BOOK3S
b3c5d3c2a49602 Alexander Graf 2012-01-07 1170 case KVM_MMIO_REG_QPR:
b3c5d3c2a49602 Alexander Graf 2012-01-07 1171 vcpu->arch.qpr[vcpu->arch.io_gpr & KVM_MMIO_REG_MASK] = gpr;
b104d06632d089 Alexander Graf 2010-02-19 1172 break;
b3c5d3c2a49602 Alexander Graf 2012-01-07 1173 case KVM_MMIO_REG_FQPR:
efff19122315f1 Paul Mackerras 2013-10-15 1174 VCPU_FPR(vcpu, vcpu->arch.io_gpr & KVM_MMIO_REG_MASK) = gpr;
b3c5d3c2a49602 Alexander Graf 2012-01-07 1175 vcpu->arch.qpr[vcpu->arch.io_gpr & KVM_MMIO_REG_MASK] = gpr;
b104d06632d089 Alexander Graf 2010-02-19 1176 break;
6f63e81bda98cb Bin Lu 2017-02-21 1177 #endif
6f63e81bda98cb Bin Lu 2017-02-21 1178 #ifdef CONFIG_VSX
6f63e81bda98cb Bin Lu 2017-02-21 1179 case KVM_MMIO_REG_VSX:
2e6baa46b4ae78 Simon Guo 2018-05-21 1180 if (vcpu->kvm->arch.kvm_ops->giveup_ext)
2e6baa46b4ae78 Simon Guo 2018-05-21 1181 vcpu->kvm->arch.kvm_ops->giveup_ext(vcpu, MSR_VSX);
2e6baa46b4ae78 Simon Guo 2018-05-21 1182
da2a32b876e979 Simon Guo 2018-05-21 1183 if (vcpu->arch.mmio_copy_type == KVMPPC_VSX_COPY_DWORD)
6f63e81bda98cb Bin Lu 2017-02-21 1184 kvmppc_set_vsr_dword(vcpu, gpr);
da2a32b876e979 Simon Guo 2018-05-21 1185 else if (vcpu->arch.mmio_copy_type == KVMPPC_VSX_COPY_WORD)
6f63e81bda98cb Bin Lu 2017-02-21 1186 kvmppc_set_vsr_word(vcpu, gpr);
da2a32b876e979 Simon Guo 2018-05-21 1187 else if (vcpu->arch.mmio_copy_type ==
6f63e81bda98cb Bin Lu 2017-02-21 1188 KVMPPC_VSX_COPY_DWORD_LOAD_DUMP)
6f63e81bda98cb Bin Lu 2017-02-21 1189 kvmppc_set_vsr_dword_dump(vcpu, gpr);
da2a32b876e979 Simon Guo 2018-05-21 1190 else if (vcpu->arch.mmio_copy_type ==
94dd7fa1c0b75e Simon Guo 2018-05-21 1191 KVMPPC_VSX_COPY_WORD_LOAD_DUMP)
94dd7fa1c0b75e Simon Guo 2018-05-21 1192 kvmppc_set_vsr_word_dump(vcpu, gpr);
6f63e81bda98cb Bin Lu 2017-02-21 1193 break;
09f984961c137c Jose Ricardo Ziviani 2018-02-03 1194 #endif
09f984961c137c Jose Ricardo Ziviani 2018-02-03 1195 #ifdef CONFIG_ALTIVEC
09f984961c137c Jose Ricardo Ziviani 2018-02-03 1196 case KVM_MMIO_REG_VMX:
2e6baa46b4ae78 Simon Guo 2018-05-21 1197 if (vcpu->kvm->arch.kvm_ops->giveup_ext)
2e6baa46b4ae78 Simon Guo 2018-05-21 1198 vcpu->kvm->arch.kvm_ops->giveup_ext(vcpu, MSR_VEC);
2e6baa46b4ae78 Simon Guo 2018-05-21 1199
acc9eb9305fecd Simon Guo 2018-05-21 1200 if (vcpu->arch.mmio_copy_type == KVMPPC_VMX_COPY_DWORD)
09f984961c137c Jose Ricardo Ziviani 2018-02-03 1201 kvmppc_set_vmx_dword(vcpu, gpr);
acc9eb9305fecd Simon Guo 2018-05-21 1202 else if (vcpu->arch.mmio_copy_type == KVMPPC_VMX_COPY_WORD)
acc9eb9305fecd Simon Guo 2018-05-21 1203 kvmppc_set_vmx_word(vcpu, gpr);
acc9eb9305fecd Simon Guo 2018-05-21 1204 else if (vcpu->arch.mmio_copy_type ==
acc9eb9305fecd Simon Guo 2018-05-21 1205 KVMPPC_VMX_COPY_HWORD)
acc9eb9305fecd Simon Guo 2018-05-21 1206 kvmppc_set_vmx_hword(vcpu, gpr);
acc9eb9305fecd Simon Guo 2018-05-21 1207 else if (vcpu->arch.mmio_copy_type ==
acc9eb9305fecd Simon Guo 2018-05-21 1208 KVMPPC_VMX_COPY_BYTE)
acc9eb9305fecd Simon Guo 2018-05-21 1209 kvmppc_set_vmx_byte(vcpu, gpr);
09f984961c137c Jose Ricardo Ziviani 2018-02-03 1210 break;
873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 1211 #endif
873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 1212 #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 1213 case KVM_MMIO_REG_NESTED_GPR:
873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 1214 if (kvmppc_need_byteswap(vcpu))
873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 1215 gpr = swab64(gpr);
873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 1216 kvm_vcpu_write_guest(vcpu, vcpu->arch.nested_io_gpr, &gpr,
873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 1217 sizeof(gpr));
873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 1218 break;
287d5611fab5a4 Alexander Graf 2010-04-01 1219 #endif
b104d06632d089 Alexander Graf 2010-02-19 1220 default:
b104d06632d089 Alexander Graf 2010-02-19 1221 BUG();
b104d06632d089 Alexander Graf 2010-02-19 1222 }
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1223 }
bbf45ba57eaec5 Hollis Blanchard 2008-04-16 1224
:::::: The code at line 1141 was first introduced by commit
:::::: 6f63e81bda98cbb549b01faf978884692ded438d KVM: PPC: Book3S: Add MMIO emulation for FP and VSX instructions
:::::: TO: Bin Lu <lblulb@linux.vnet.ibm.com>
:::::: CC: Paul Mackerras <paulus@ozlabs.org>
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: arch/powerpc/kvm/powerpc.c:1141:7: warning: Redundant assignment of 'gpr' to itself. [selfAssignment]
2021-06-25 14:07 arch/powerpc/kvm/powerpc.c:1141:7: warning: Redundant assignment of 'gpr' to itself. [selfAssignment] kernel test robot
@ 2021-06-26 10:28 ` Michael Ellerman
0 siblings, 0 replies; 2+ messages in thread
From: Michael Ellerman @ 2021-06-26 10:28 UTC (permalink / raw)
To: kernel test robot, Cédric Le Goater; +Cc: kbuild-all, linux-kernel
kernel test robot <lkp@intel.com> writes:
> Hi Cédric,
>
> First bad commit (maybe != root cause):
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 44db63d1ad8d71c6932cbe007eb41f31c434d140
> commit: 9236f57a9e51c72ce426ccd2e53e123de7196a0f KVM: PPC: Make the VMX instruction emulation routines static
> date: 5 months ago
> compiler: powerpc64-linux-gcc (GCC) 9.3.0
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
>
> cppcheck warnings: (new ones prefixed by >>)
>>> arch/powerpc/kvm/powerpc.c:1141:7: warning: Redundant assignment of 'gpr' to itself. [selfAssignment]
> gpr = sp_to_dp(gpr);
> ^
>>> arch/powerpc/kvm/powerpc.c:1341:7: warning: Redundant assignment of 'val' to itself. [selfAssignment]
> val = dp_to_sp(val);
Because of:
#ifdef CONFIG_PPC_FPU
static inline u64 sp_to_dp(u32 fprs)
{
u64 fprd;
preempt_disable();
enable_kernel_fp();
asm ("lfs%U1%X1 0,%1; stfd%U0%X0 0,%0" : "=m"UPD_CONSTR (fprd) : "m"UPD_CONSTR (fprs)
: "fr0");
preempt_enable();
return fprd;
}
static inline u32 dp_to_sp(u64 fprd)
{
u32 fprs;
preempt_disable();
enable_kernel_fp();
asm ("lfd%U1%X1 0,%1; stfs%U0%X0 0,%0" : "=m"UPD_CONSTR (fprs) : "m"UPD_CONSTR (fprd)
: "fr0");
preempt_enable();
return fprs;
}
#else
#define sp_to_dp(x) (x)
#define dp_to_sp(x) (x)
#endif /* CONFIG_PPC_FPU */
And you must be building the PPC_FPU=n case.
Surely the compiler is smart enough to generate no code for this. So
what's the harm? ie. why is this something we should be fixing?
cheers
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-06-25 14:07 arch/powerpc/kvm/powerpc.c:1141:7: warning: Redundant assignment of 'gpr' to itself. [selfAssignment] kernel test robot
2021-06-26 10:28 ` Michael Ellerman
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