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Message-ID: <e6167885-30e5-d149-bcde-3e9ad9f5d381@kernel.org>
Date: Sun, 20 Jun 2021 22:53:22 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Nicholas Piggin <npiggin@...il.com>, Arnd Bergmann <arnd@...db.de>,
kernel test robot <lkp@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
clang-built-linux@...glegroups.com, kbuild-all@...ts.01.org,
Kees Cook <keescook@...omium.org>,
linux-kernel@...r.kernel.org,
Linux Memory Management List <linux-mm@...ck.org>,
linuxppc-dev@...ts.ozlabs.org, kvm-ppc@...r.kernel.org
Subject: Re: arch/powerpc/kvm/book3s_hv_nested.c:264:6: error: stack frame
size of 2304 bytes in function 'kvmhv_enter_nested_guest'
On 6/20/2021 4:59 PM, Nicholas Piggin wrote:
> Excerpts from kernel test robot's message of April 3, 2021 8:47 pm:
>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>> head: d93a0d43e3d0ba9e19387be4dae4a8d5b175a8d7
>> commit: 97e4910232fa1f81e806aa60c25a0450276d99a2 linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP*
>> date: 3 weeks ago
>> config: powerpc64-randconfig-r006-20210403 (attached as .config)
>> compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 0fe8af94688aa03c01913c2001d6a1a911f42ce6)
>> reproduce (this is a W=1 build):
>> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>> chmod +x ~/bin/make.cross
>> # install powerpc64 cross compiling tool for clang build
>> # apt-get install binutils-powerpc64-linux-gnu
>> # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=97e4910232fa1f81e806aa60c25a0450276d99a2
>> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>> git fetch --no-tags linus master
>> git checkout 97e4910232fa1f81e806aa60c25a0450276d99a2
>> # save the attached .config to linux build tree
>> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc64
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@...el.com>
>>
>> All errors (new ones prefixed by >>):
>>
>>>> arch/powerpc/kvm/book3s_hv_nested.c:264:6: error: stack frame size of 2304 bytes in function 'kvmhv_enter_nested_guest' [-Werror,-Wframe-larger-than=]
>> long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu)
>> ^
>> 1 error generated.
>>
>>
>> vim +/kvmhv_enter_nested_guest +264 arch/powerpc/kvm/book3s_hv_nested.c
>
> Not much changed here recently. It's not that big a concern because it's
> only called in the KVM ioctl path, not in any deep IO paths or anything,
> and doesn't recurse. Might be a bit of inlining or stack spilling put it
> over the edge.
It appears to be the fact that LLVM's PowerPC backend does not emit
efficient byteswap assembly:
https://github.com/ClangBuiltLinux/linux/issues/1292
https://bugs.llvm.org/show_bug.cgi?id=49610
> powerpc does make it an error though, would be good to avoid that so the
> robot doesn't keep tripping over.
Marking byteswap_pt_regs as 'noinline_for_stack' drastically reduces the
stack usage. If that is an acceptable solution, I can send it along
tomorrow.
Cheers,
Nathan
> Thanks,
> Nick
>
>
>>
>> afe75049303f75 Ravi Bangoria 2020-12-16 263
>> 360cae313702cd Paul Mackerras 2018-10-08 @264 long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu)
>> 360cae313702cd Paul Mackerras 2018-10-08 265 {
>> 360cae313702cd Paul Mackerras 2018-10-08 266 long int err, r;
>> 360cae313702cd Paul Mackerras 2018-10-08 267 struct kvm_nested_guest *l2;
>> 360cae313702cd Paul Mackerras 2018-10-08 268 struct pt_regs l2_regs, saved_l1_regs;
>> afe75049303f75 Ravi Bangoria 2020-12-16 269 struct hv_guest_state l2_hv = {0}, saved_l1_hv;
>> 360cae313702cd Paul Mackerras 2018-10-08 270 struct kvmppc_vcore *vc = vcpu->arch.vcore;
>> 360cae313702cd Paul Mackerras 2018-10-08 271 u64 hv_ptr, regs_ptr;
>> 360cae313702cd Paul Mackerras 2018-10-08 272 u64 hdec_exp;
>> 360cae313702cd Paul Mackerras 2018-10-08 273 s64 delta_purr, delta_spurr, delta_ic, delta_vtb;
>> 360cae313702cd Paul Mackerras 2018-10-08 274 u64 mask;
>> 360cae313702cd Paul Mackerras 2018-10-08 275 unsigned long lpcr;
>> 360cae313702cd Paul Mackerras 2018-10-08 276
>> 360cae313702cd Paul Mackerras 2018-10-08 277 if (vcpu->kvm->arch.l1_ptcr == 0)
>> 360cae313702cd Paul Mackerras 2018-10-08 278 return H_NOT_AVAILABLE;
>> 360cae313702cd Paul Mackerras 2018-10-08 279
>> 360cae313702cd Paul Mackerras 2018-10-08 280 /* copy parameters in */
>> 360cae313702cd Paul Mackerras 2018-10-08 281 hv_ptr = kvmppc_get_gpr(vcpu, 4);
>> 1508c22f112ce1 Alexey Kardashevskiy 2020-06-09 282 regs_ptr = kvmppc_get_gpr(vcpu, 5);
>> 1508c22f112ce1 Alexey Kardashevskiy 2020-06-09 283 vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
>> afe75049303f75 Ravi Bangoria 2020-12-16 284 err = kvmhv_read_guest_state_and_regs(vcpu, &l2_hv, &l2_regs,
>> afe75049303f75 Ravi Bangoria 2020-12-16 285 hv_ptr, regs_ptr);
>> 1508c22f112ce1 Alexey Kardashevskiy 2020-06-09 286 srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
>> 360cae313702cd Paul Mackerras 2018-10-08 287 if (err)
>> 360cae313702cd Paul Mackerras 2018-10-08 288 return H_PARAMETER;
>> 1508c22f112ce1 Alexey Kardashevskiy 2020-06-09 289
>> 10b5022db7861a Suraj Jitindar Singh 2018-10-08 290 if (kvmppc_need_byteswap(vcpu))
>> 10b5022db7861a Suraj Jitindar Singh 2018-10-08 291 byteswap_hv_regs(&l2_hv);
>> afe75049303f75 Ravi Bangoria 2020-12-16 292 if (l2_hv.version > HV_GUEST_STATE_VERSION)
>> 360cae313702cd Paul Mackerras 2018-10-08 293 return H_P2;
>> 360cae313702cd Paul Mackerras 2018-10-08 294
>> 10b5022db7861a Suraj Jitindar Singh 2018-10-08 295 if (kvmppc_need_byteswap(vcpu))
>> 10b5022db7861a Suraj Jitindar Singh 2018-10-08 296 byteswap_pt_regs(&l2_regs);
>> 9d0b048da788c1 Suraj Jitindar Singh 2018-10-08 297 if (l2_hv.vcpu_token >= NR_CPUS)
>> 9d0b048da788c1 Suraj Jitindar Singh 2018-10-08 298 return H_PARAMETER;
>> 9d0b048da788c1 Suraj Jitindar Singh 2018-10-08 299
>> 360cae313702cd Paul Mackerras 2018-10-08 300 /* translate lpid */
>> 360cae313702cd Paul Mackerras 2018-10-08 301 l2 = kvmhv_get_nested(vcpu->kvm, l2_hv.lpid, true);
>> 360cae313702cd Paul Mackerras 2018-10-08 302 if (!l2)
>> 360cae313702cd Paul Mackerras 2018-10-08 303 return H_PARAMETER;
>> 360cae313702cd Paul Mackerras 2018-10-08 304 if (!l2->l1_gr_to_hr) {
>> 360cae313702cd Paul Mackerras 2018-10-08 305 mutex_lock(&l2->tlb_lock);
>> 360cae313702cd Paul Mackerras 2018-10-08 306 kvmhv_update_ptbl_cache(l2);
>> 360cae313702cd Paul Mackerras 2018-10-08 307 mutex_unlock(&l2->tlb_lock);
>> 360cae313702cd Paul Mackerras 2018-10-08 308 }
>> 360cae313702cd Paul Mackerras 2018-10-08 309
>> 360cae313702cd Paul Mackerras 2018-10-08 310 /* save l1 values of things */
>> 360cae313702cd Paul Mackerras 2018-10-08 311 vcpu->arch.regs.msr = vcpu->arch.shregs.msr;
>> 360cae313702cd Paul Mackerras 2018-10-08 312 saved_l1_regs = vcpu->arch.regs;
>> 360cae313702cd Paul Mackerras 2018-10-08 313 kvmhv_save_hv_regs(vcpu, &saved_l1_hv);
>> 360cae313702cd Paul Mackerras 2018-10-08 314
>> 360cae313702cd Paul Mackerras 2018-10-08 315 /* convert TB values/offsets to host (L0) values */
>> 360cae313702cd Paul Mackerras 2018-10-08 316 hdec_exp = l2_hv.hdec_expiry - vc->tb_offset;
>> 360cae313702cd Paul Mackerras 2018-10-08 317 vc->tb_offset += l2_hv.tb_offset;
>> 360cae313702cd Paul Mackerras 2018-10-08 318
>> 360cae313702cd Paul Mackerras 2018-10-08 319 /* set L1 state to L2 state */
>> 360cae313702cd Paul Mackerras 2018-10-08 320 vcpu->arch.nested = l2;
>> 360cae313702cd Paul Mackerras 2018-10-08 321 vcpu->arch.nested_vcpu_id = l2_hv.vcpu_token;
>> 360cae313702cd Paul Mackerras 2018-10-08 322 vcpu->arch.regs = l2_regs;
>> 360cae313702cd Paul Mackerras 2018-10-08 323 vcpu->arch.shregs.msr = vcpu->arch.regs.msr;
>> 360cae313702cd Paul Mackerras 2018-10-08 324 mask = LPCR_DPFD | LPCR_ILE | LPCR_TC | LPCR_AIL | LPCR_LD |
>> 360cae313702cd Paul Mackerras 2018-10-08 325 LPCR_LPES | LPCR_MER;
>> 360cae313702cd Paul Mackerras 2018-10-08 326 lpcr = (vc->lpcr & ~mask) | (l2_hv.lpcr & mask);
>> 73937deb4b2d7f Suraj Jitindar Singh 2018-10-08 327 sanitise_hv_regs(vcpu, &l2_hv);
>> 360cae313702cd Paul Mackerras 2018-10-08 328 restore_hv_regs(vcpu, &l2_hv);
>> 360cae313702cd Paul Mackerras 2018-10-08 329
>> 360cae313702cd Paul Mackerras 2018-10-08 330 vcpu->arch.ret = RESUME_GUEST;
>> 360cae313702cd Paul Mackerras 2018-10-08 331 vcpu->arch.trap = 0;
>> 360cae313702cd Paul Mackerras 2018-10-08 332 do {
>> 360cae313702cd Paul Mackerras 2018-10-08 333 if (mftb() >= hdec_exp) {
>> 360cae313702cd Paul Mackerras 2018-10-08 334 vcpu->arch.trap = BOOK3S_INTERRUPT_HV_DECREMENTER;
>> 360cae313702cd Paul Mackerras 2018-10-08 335 r = RESUME_HOST;
>> 360cae313702cd Paul Mackerras 2018-10-08 336 break;
>> 360cae313702cd Paul Mackerras 2018-10-08 337 }
>> 8c99d34578628b Tianjia Zhang 2020-04-27 338 r = kvmhv_run_single_vcpu(vcpu, hdec_exp, lpcr);
>> 360cae313702cd Paul Mackerras 2018-10-08 339 } while (is_kvmppc_resume_guest(r));
>> 360cae313702cd Paul Mackerras 2018-10-08 340
>> 360cae313702cd Paul Mackerras 2018-10-08 341 /* save L2 state for return */
>> 360cae313702cd Paul Mackerras 2018-10-08 342 l2_regs = vcpu->arch.regs;
>> 360cae313702cd Paul Mackerras 2018-10-08 343 l2_regs.msr = vcpu->arch.shregs.msr;
>> 360cae313702cd Paul Mackerras 2018-10-08 344 delta_purr = vcpu->arch.purr - l2_hv.purr;
>> 360cae313702cd Paul Mackerras 2018-10-08 345 delta_spurr = vcpu->arch.spurr - l2_hv.spurr;
>> 360cae313702cd Paul Mackerras 2018-10-08 346 delta_ic = vcpu->arch.ic - l2_hv.ic;
>> 360cae313702cd Paul Mackerras 2018-10-08 347 delta_vtb = vc->vtb - l2_hv.vtb;
>> 360cae313702cd Paul Mackerras 2018-10-08 348 save_hv_return_state(vcpu, vcpu->arch.trap, &l2_hv);
>> 360cae313702cd Paul Mackerras 2018-10-08 349
>> 360cae313702cd Paul Mackerras 2018-10-08 350 /* restore L1 state */
>> 360cae313702cd Paul Mackerras 2018-10-08 351 vcpu->arch.nested = NULL;
>> 360cae313702cd Paul Mackerras 2018-10-08 352 vcpu->arch.regs = saved_l1_regs;
>> 360cae313702cd Paul Mackerras 2018-10-08 353 vcpu->arch.shregs.msr = saved_l1_regs.msr & ~MSR_TS_MASK;
>> 360cae313702cd Paul Mackerras 2018-10-08 354 /* set L1 MSR TS field according to L2 transaction state */
>> 360cae313702cd Paul Mackerras 2018-10-08 355 if (l2_regs.msr & MSR_TS_MASK)
>> 360cae313702cd Paul Mackerras 2018-10-08 356 vcpu->arch.shregs.msr |= MSR_TS_S;
>> 360cae313702cd Paul Mackerras 2018-10-08 357 vc->tb_offset = saved_l1_hv.tb_offset;
>> 360cae313702cd Paul Mackerras 2018-10-08 358 restore_hv_regs(vcpu, &saved_l1_hv);
>> 360cae313702cd Paul Mackerras 2018-10-08 359 vcpu->arch.purr += delta_purr;
>> 360cae313702cd Paul Mackerras 2018-10-08 360 vcpu->arch.spurr += delta_spurr;
>> 360cae313702cd Paul Mackerras 2018-10-08 361 vcpu->arch.ic += delta_ic;
>> 360cae313702cd Paul Mackerras 2018-10-08 362 vc->vtb += delta_vtb;
>> 360cae313702cd Paul Mackerras 2018-10-08 363
>> 360cae313702cd Paul Mackerras 2018-10-08 364 kvmhv_put_nested(l2);
>> 360cae313702cd Paul Mackerras 2018-10-08 365
>> 360cae313702cd Paul Mackerras 2018-10-08 366 /* copy l2_hv_state and regs back to guest */
>> 10b5022db7861a Suraj Jitindar Singh 2018-10-08 367 if (kvmppc_need_byteswap(vcpu)) {
>> 10b5022db7861a Suraj Jitindar Singh 2018-10-08 368 byteswap_hv_regs(&l2_hv);
>> 10b5022db7861a Suraj Jitindar Singh 2018-10-08 369 byteswap_pt_regs(&l2_regs);
>> 10b5022db7861a Suraj Jitindar Singh 2018-10-08 370 }
>> 1508c22f112ce1 Alexey Kardashevskiy 2020-06-09 371 vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
>> afe75049303f75 Ravi Bangoria 2020-12-16 372 err = kvmhv_write_guest_state_and_regs(vcpu, &l2_hv, &l2_regs,
>> afe75049303f75 Ravi Bangoria 2020-12-16 373 hv_ptr, regs_ptr);
>> 1508c22f112ce1 Alexey Kardashevskiy 2020-06-09 374 srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
>> 360cae313702cd Paul Mackerras 2018-10-08 375 if (err)
>> 360cae313702cd Paul Mackerras 2018-10-08 376 return H_AUTHORITY;
>> 360cae313702cd Paul Mackerras 2018-10-08 377
>> 360cae313702cd Paul Mackerras 2018-10-08 378 if (r == -EINTR)
>> 360cae313702cd Paul Mackerras 2018-10-08 379 return H_INTERRUPT;
>> 360cae313702cd Paul Mackerras 2018-10-08 380
>> 873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 381 if (vcpu->mmio_needed) {
>> 873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 382 kvmhv_nested_mmio_needed(vcpu, regs_ptr);
>> 873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 383 return H_TOO_HARD;
>> 873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 384 }
>> 873db2cd9a6d7f Suraj Jitindar Singh 2018-12-14 385
>> 360cae313702cd Paul Mackerras 2018-10-08 386 return vcpu->arch.trap;
>> 360cae313702cd Paul Mackerras 2018-10-08 387 }
>> 360cae313702cd Paul Mackerras 2018-10-08 388
>>
>> :::::: The code at line 264 was first introduced by commit
>> :::::: 360cae313702cdd0b90f82c261a8302fecef030a KVM: PPC: Book3S HV: Nested guest entry via hypercall
>>
>> :::::: TO: Paul Mackerras <paulus@...abs.org>
>> :::::: CC: Michael Ellerman <mpe@...erman.id.au>
>>
>> ---
>> 0-DAY CI Kernel Test Service, Intel Corporation
>> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>>
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