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[34.77.126.161]) by smtp.gmail.com with ESMTPSA id je11-20020a05600c1f8b00b0040fdf5e6d40sm22277768wmb.20.2024.02.22.07.17.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Feb 2024 07:17:04 -0800 (PST) Date: Thu, 22 Feb 2024 15:17:02 +0000 From: Sebastian Ene To: catalin.marinas@arm.com, gshan@redhat.com, james.morse@arm.com, mark.rutland@arm.com, maz@kernel.org, oliver.upton@linux.dev, rananta@google.com, ricarkol@google.com, ryan.roberts@arm.com, shahuang@redhat.com, suzuki.poulose@arm.com, will@kernel.org, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel-team@android.com, vdonnefort@google.com Subject: Re: [PATCH v6 4/6] KVM: arm64: Register ptdump with debugfs on guest creation Message-ID: References: <20240220151035.327199-1-sebastianene@google.com> <20240220151035.327199-5-sebastianene@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240220151035.327199-5-sebastianene@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240222_071708_288876_0F8235EB X-CRM114-Status: GOOD ( 32.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Feb 20, 2024 at 03:10:33PM +0000, Sebastian Ene wrote: > While arch/*/mem/ptdump handles the kernel pagetable dumping code, > introduce KVM/ptdump which shows the guest stage-2 pagetables. The > separation is necessary because most of the definitions from the > stage-2 pagetable reside in the KVM path and we will be invoking > functionality **specific** to KVM. > > When a guest is created, register a new file entry under the guest > debugfs dir which allows userspace to show the contents of the guest > stage-2 pagetables when accessed. > > Signed-off-by: Sebastian Ene > --- > arch/arm64/kvm/Kconfig | 13 ++++++ > arch/arm64/kvm/Makefile | 1 + > arch/arm64/kvm/debug.c | 8 ++++ > arch/arm64/kvm/kvm_ptdump.h | 20 +++++++++ > arch/arm64/kvm/ptdump.c | 88 +++++++++++++++++++++++++++++++++++++ > 5 files changed, 130 insertions(+) > create mode 100644 arch/arm64/kvm/kvm_ptdump.h > create mode 100644 arch/arm64/kvm/ptdump.c > > diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig > index 27ca89b628a0..83ca07d16cf4 100644 > --- a/arch/arm64/kvm/Kconfig > +++ b/arch/arm64/kvm/Kconfig > @@ -67,4 +67,17 @@ config PROTECTED_NVHE_STACKTRACE > > If unsure, or not using protected nVHE (pKVM), say N. > > +config PTDUMP_STAGE2_DEBUGFS > + bool "Present the stage-2 pagetables to debugfs" > + depends on PTDUMP_DEBUGFS && KVM > + default n > + help > + Say Y here if you want to show the stage-2 kernel pagetables > + layout in a debugfs file. This information is only useful for kernel developers > + who are working in architecture specific areas of the kernel. > + It is probably not a good idea to enable this feature in a production > + kernel. > + > + If in doubt, say N. > + > endif # VIRTUALIZATION > diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile > index c0c050e53157..190eac17538c 100644 > --- a/arch/arm64/kvm/Makefile > +++ b/arch/arm64/kvm/Makefile > @@ -23,6 +23,7 @@ kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \ > vgic/vgic-its.o vgic/vgic-debug.o > > kvm-$(CONFIG_HW_PERF_EVENTS) += pmu-emul.o pmu.o > +kvm-$(CONFIG_PTDUMP_STAGE2_DEBUGFS) += ptdump.o > > always-y := hyp_constants.h hyp-constants.s > > diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c > index 8725291cb00a..ff97af2c0513 100644 > --- a/arch/arm64/kvm/debug.c > +++ b/arch/arm64/kvm/debug.c > @@ -14,6 +14,8 @@ > #include > #include > > +#include > + > #include "trace.h" > > /* These are the bits of MDSCR_EL1 we may manipulate */ > @@ -342,3 +344,9 @@ void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu) > vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_SPE); > vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_TRBE); > } > + > +int kvm_arch_create_vm_debugfs(struct kvm *kvm) > +{ > + kvm_ptdump_guest_register(kvm); > + return 0; > +} > diff --git a/arch/arm64/kvm/kvm_ptdump.h b/arch/arm64/kvm/kvm_ptdump.h > new file mode 100644 > index 000000000000..5e8a655605f1 > --- /dev/null > +++ b/arch/arm64/kvm/kvm_ptdump.h > @@ -0,0 +1,20 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) Google, 2023 > + * Author: Sebastian Ene > + */ > + > +#ifndef __KVM_PTDUMP_H > +#define __KVM_PTDUMP_H > + > +#include > +#include > + > + > +#ifdef CONFIG_PTDUMP_STAGE2_DEBUGFS > +void kvm_ptdump_guest_register(struct kvm *kvm); > +#else > +static inline void kvm_ptdump_guest_register(struct kvm *kvm) {} > +#endif /* CONFIG_PTDUMP_STAGE2_DEBUGFS */ > + > +#endif /* __KVM_PTDUMP_H */ > diff --git a/arch/arm64/kvm/ptdump.c b/arch/arm64/kvm/ptdump.c > new file mode 100644 > index 000000000000..9b04c24bb9be > --- /dev/null > +++ b/arch/arm64/kvm/ptdump.c > @@ -0,0 +1,88 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Debug helper used to dump the stage-2 pagetables of the system and their > + * associated permissions. > + * > + * Copyright (C) Google, 2023 > + * Author: Sebastian Ene > + */ > +#include > +#include > +#include > + > +#include > +#include > + > + > +static int kvm_ptdump_visitor(const struct kvm_pgtable_visit_ctx *ctx, > + enum kvm_pgtable_walk_flags visit) > +{ > + struct pg_state *st = ctx->arg; > + struct ptdump_state *pt_st = &st->ptdump; > + > + note_page(pt_st, ctx->addr, ctx->level, ctx->old); > + return 0; > +} > + > +static int kvm_ptdump_show_common(struct seq_file *m, > + struct kvm_pgtable *pgtable, > + struct pg_state *parser_state) > +{ > + struct kvm_pgtable_walker walker = (struct kvm_pgtable_walker) { > + .cb = kvm_ptdump_visitor, > + .arg = parser_state, > + .flags = KVM_PGTABLE_WALK_LEAF, > + }; > + > + return kvm_pgtable_walk(pgtable, 0, BIT(pgtable->ia_bits), &walker); > +} > + > +static int kvm_ptdump_guest_show(struct seq_file *m, void *) ^ FIXME: Here I need to specify an argument name as building with clang complaints about this. > +{ > + struct kvm *kvm = m->private; > + struct kvm_s2_mmu *mmu = &kvm->arch.mmu; > + struct pg_state parser_state = {0}; > + int ret; > + > + write_lock(&kvm->mmu_lock); > + ret = kvm_ptdump_show_common(m, mmu->pgt, &parser_state); > + write_unlock(&kvm->mmu_lock); > + > + return ret; > +} > + > +static int kvm_ptdump_guest_open(struct inode *m, struct file *file) > +{ > + struct kvm *kvm = m->i_private; > + int ret; > + > + if (!kvm_get_kvm_safe(kvm)) > + return -ENOENT; > + > + ret = single_open(file, kvm_ptdump_guest_show, m->i_private); > + if (ret < 0) > + kvm_put_kvm(kvm); > + > + return ret; > +} > + > +static int kvm_ptdump_guest_close(struct inode *m, struct file *file) > +{ > + struct kvm *kvm = m->i_private; > + > + kvm_put_kvm(kvm); > + return single_release(m, file); > +} > + > +static const struct file_operations kvm_ptdump_guest_fops = { > + .open = kvm_ptdump_guest_open, > + .read = seq_read, > + .llseek = seq_lseek, > + .release = kvm_ptdump_guest_close, > +}; > + > +void kvm_ptdump_guest_register(struct kvm *kvm) > +{ > + debugfs_create_file("stage2_page_tables", 0400, kvm->debugfs_dentry, > + kvm, &kvm_ptdump_guest_fops); > +} > -- > 2.44.0.rc0.258.g7320e95886-goog > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel