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Thu, 10 Oct 2024 14:24:08 -0700 (PDT) X-Google-Smtp-Source: AGHT+IH15rRMAVXsYsvGP3nHpjiqsOwqxS4ttKi4hWbrl20imAxCjoxkwTI5t6kkZa8FMv1uivlQnA== X-Received: by 2002:a17:907:e2c2:b0:a99:50b8:9a10 with SMTP id a640c23a62f3a-a99b95e5ff5mr26359666b.64.1728595447686; Thu, 10 Oct 2024 14:24:07 -0700 (PDT) Received: from [192.168.10.3] ([151.81.124.37]) by smtp.googlemail.com with ESMTPSA id a640c23a62f3a-a99a80dc502sm139723466b.146.2024.10.10.14.24.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 10 Oct 2024 14:24:07 -0700 (PDT) Message-ID: <640d6536-e1b3-4ca8-99f8-676e8905cc3e@redhat.com> Date: Thu, 10 Oct 2024 23:23:55 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] powerpc/kvm: Fix spinlock member access for PREEMPT_RT To: Vishal Chourasia , linuxppc-dev@lists.ozlabs.org, Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Madhavan Srinivasan , kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: From: Paolo Bonzini Content-Language: en-US Autocrypt: addr=pbonzini@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/10/24 20:09, Vishal Chourasia wrote: > Hi, > > While building the kernel with CONFIG_PREEMPT_RT, I encountered several > compilation errors in the PowerPC KVM code. The issues appear in > book3s_hv_rm_mmu.c where it tries to access the 'rlock' member of struct > spinlock, which doesn't exist in the RT configuration. How was this tested? I suspect that putting to sleep a task that is running in real mode is a huge no-no. The actual solution would have to be to split mmu_lock into a spin_lock and a raw_spin_lock, but that's a huge amount of work probably. I'd just add a "depends on !PPC || !KVM_BOOK3S_64_HV" or something like that, to prevent enabling KVM-HV on PREEMPT_RT kernels. Thanks, Paolo > arch/powerpc/kvm/book3s_hv_rm_mmu.c:248:32: error: no member named 'rlock' in 'struct spinlock' > 248 | arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock); > | ~~~~~~~~~~~~~ ^ > ./arch/powerpc/include/asm/qspinlock.h:164:45: note: expanded from macro 'arch_spin_lock' > 164 | #define arch_spin_lock(l) queued_spin_lock(l) > | ^ > arch/powerpc/kvm/book3s_hv_rm_mmu.c:263:36: error: no member named 'rlock' in 'struct spinlock' > 263 | arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock); > | ~~~~~~~~~~~~~ ^ > ./arch/powerpc/include/asm/qspinlock.h:166:49: note: expanded from macro 'arch_spin_unlock' > 166 | #define arch_spin_unlock(l) queued_spin_unlock(l) > | ^ > arch/powerpc/kvm/book3s_hv_rm_mmu.c:277:34: error: no member named 'rlock' in 'struct spinlock' > 277 | arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock); > | ~~~~~~~~~~~~~ ^ > ./arch/powerpc/include/asm/qspinlock.h:166:49: note: expanded from macro 'arch_spin_unlock' > 166 | #define arch_spin_unlock(l) queued_spin_unlock(l) > | ^ > arch/powerpc/kvm/book3s_hv_rm_mmu.c:938:32: error: no member named 'rlock' in 'struct spinlock' > 938 | arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock); > | ~~~~~~~~~~~~~ ^ > ./arch/powerpc/include/asm/qspinlock.h:164:45: note: expanded from macro 'arch_spin_lock' > 164 | #define arch_spin_lock(l) queued_spin_lock(l) > | ^ > arch/powerpc/kvm/book3s_hv_rm_mmu.c:950:34: error: no member named 'rlock' in 'struct spinlock' > 950 | arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock); > | ~~~~~~~~~~~~~ ^ > ./arch/powerpc/include/asm/qspinlock.h:166:49: note: expanded from macro 'arch_spin_unlock' > 166 | #define arch_spin_unlock(l) queued_spin_unlock(l) > | ^ > arch/powerpc/kvm/book3s_hv_rm_mmu.c:966:32: error: no member named 'rlock' in 'struct spinlock' > 966 | arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock); > | ~~~~~~~~~~~~~ ^ > ./arch/powerpc/include/asm/qspinlock.h:164:45: note: expanded from macro 'arch_spin_lock' > 164 | #define arch_spin_lock(l) queued_spin_lock(l) > | ^ > arch/powerpc/kvm/book3s_hv_rm_mmu.c:981:34: error: no member named 'rlock' in 'struct spinlock' > 981 | arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock); > | ~~~~~~~~~~~~~ ^ > ./arch/powerpc/include/asm/qspinlock.h:166:49: note: expanded from macro 'arch_spin_unlock' > 166 | #define arch_spin_unlock(l) queued_spin_unlock(l) > | ^ > 7 errors generated. > make[4]: *** [scripts/Makefile.build:229: arch/powerpc/kvm/book3s_hv_rm_mmu.o] Error 1 > make[3]: *** [scripts/Makefile.build:478: arch/powerpc/kvm] Error 2 > make[3]: *** Waiting for unfinished jobs.... > make[2]: *** [scripts/Makefile.build:478: arch/powerpc] Error 2 > make[2]: *** Waiting for unfinished jobs.... > > Replace arch_spin_lock/unlock on kvm->mmu_lock.rlock.raw_lock with > simple spin_lock/unlock on kvm->mmu_lock to fix build errors with > CONFIG_PREEMPT_RT. The RT configuration changes the spinlock structure, > removing the rlock member. > > Signed-off-by: Vishal Chourasia > --- > arch/powerpc/kvm/book3s_hv_rm_mmu.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > index 17cb75a127b04..abf1e6de85644 100644 > --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c > +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c > @@ -245,7 +245,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, > /* Translate to host virtual address */ > hva = __gfn_to_hva_memslot(memslot, gfn); > > - arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock); > + spin_lock(&kvm->mmu_lock); > ptep = find_kvm_host_pte(kvm, mmu_seq, hva, &hpage_shift); > if (ptep) { > pte_t pte; > @@ -260,7 +260,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, > * to <= host page size, if host is using hugepage > */ > if (host_pte_size < psize) { > - arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock); > + spin_unlock(&kvm->mmu_lock); > return H_PARAMETER; > } > pte = kvmppc_read_update_linux_pte(ptep, writing); > @@ -274,7 +274,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, > pa |= gpa & ~PAGE_MASK; > } > } > - arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock); > + spin_unlock(&kvm->mmu_lock); > > ptel &= HPTE_R_KEY | HPTE_R_PP0 | (psize-1); > ptel |= pa; > @@ -935,7 +935,7 @@ static long kvmppc_do_h_page_init_zero(struct kvm_vcpu *vcpu, > mmu_seq = kvm->mmu_invalidate_seq; > smp_rmb(); > > - arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock); > + spin_lock(&kvm->mmu_lock); > > ret = kvmppc_get_hpa(vcpu, mmu_seq, dest, 1, &pa, &memslot); > if (ret != H_SUCCESS) > @@ -947,7 +947,7 @@ static long kvmppc_do_h_page_init_zero(struct kvm_vcpu *vcpu, > kvmppc_update_dirty_map(memslot, dest >> PAGE_SHIFT, PAGE_SIZE); > > out_unlock: > - arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock); > + spin_unlock(&kvm->mmu_lock); > return ret; > } > > @@ -963,7 +963,7 @@ static long kvmppc_do_h_page_init_copy(struct kvm_vcpu *vcpu, > mmu_seq = kvm->mmu_invalidate_seq; > smp_rmb(); > > - arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock); > + spin_lock(&kvm->mmu_lock); > ret = kvmppc_get_hpa(vcpu, mmu_seq, dest, 1, &dest_pa, &dest_memslot); > if (ret != H_SUCCESS) > goto out_unlock; > @@ -978,7 +978,7 @@ static long kvmppc_do_h_page_init_copy(struct kvm_vcpu *vcpu, > kvmppc_update_dirty_map(dest_memslot, dest >> PAGE_SHIFT, PAGE_SIZE); > > out_unlock: > - arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock); > + spin_unlock(&kvm->mmu_lock); > return ret; > } > > -- > 2.46.2 > >