Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Tue, 19 Dec 2023 11:47:40 +0000 | From | Sebastian Ene <> | Subject | Re: [PATCH v4 02/10] KVM: arm64: Add ptdump registration with debugfs for the stage-2 pagetables |
| |
On Mon, Dec 18, 2023 at 01:58:52PM +0000, Sebastian Ene wrote: > While arch/*/mem/ptdump handles the kernel pagetable dumping code, > introduce KVM/ptdump which deals with the 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. > > This registers a wrapper on top of debugfs_create_file which allows us > to hook callbacks on the debugfs open/show/close. The callbacks are used > to prepare the display portion of the pagetable dumping code. > Guard this functionality under the newly introduced PTDUMP_STAGE2_DEBUGFS. > > Signed-off-by: Sebastian Ene <sebastianene@google.com> > --- > arch/arm64/kvm/Kconfig | 13 +++++ > arch/arm64/kvm/Makefile | 1 + > arch/arm64/kvm/arm.c | 2 + > arch/arm64/kvm/kvm_ptdump.h | 18 +++++++ > arch/arm64/kvm/ptdump.c | 96 +++++++++++++++++++++++++++++++++++++ > 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 83c1e09be..0014e55e2 100644 > --- a/arch/arm64/kvm/Kconfig > +++ b/arch/arm64/kvm/Kconfig > @@ -71,4 +71,17 @@ 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 c0c050e53..190eac175 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/arm.c b/arch/arm64/kvm/arm.c > index e5f75f1f1..ee8d7cb67 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -40,6 +40,7 @@ > #include <asm/kvm_pkvm.h> > #include <asm/kvm_emulate.h> > #include <asm/sections.h> > +#include <kvm_ptdump.h> > > #include <kvm/arm_hypercalls.h> > #include <kvm/arm_pmu.h> > @@ -2592,6 +2593,7 @@ static __init int kvm_arm_init(void) > if (err) > goto out_subs; > > + kvm_ptdump_register_host(); > kvm_arm_initialised = true; > > return 0; > diff --git a/arch/arm64/kvm/kvm_ptdump.h b/arch/arm64/kvm/kvm_ptdump.h > new file mode 100644 > index 000000000..98b595ce8 > --- /dev/null > +++ b/arch/arm64/kvm/kvm_ptdump.h > @@ -0,0 +1,18 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +// > +// Copyright (C) Google, 2023 > +// Author: Sebastian Ene <sebastianene@google.com> > + > +#ifndef __KVM_PTDUMP_H > +#define __KVM_PTDUMP_H > + > +#include <asm/ptdump.h> > + > + > +#ifdef CONFIG_PTDUMP_STAGE2_DEBUGFS > +void kvm_ptdump_register_host(void); > +#else > +static inline void kvm_ptdump_register_host(void) { } > +#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 000000000..5816fc632 > --- /dev/null > +++ b/arch/arm64/kvm/ptdump.c > @@ -0,0 +1,96 @@ > +// 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 <sebastianene@google.com> > + > +#include <linux/debugfs.h> > +#include <linux/kvm_host.h> > +#include <linux/seq_file.h> > + > +#include <asm/kvm_pkvm.h> > +#include <kvm_ptdump.h> > + > + > +struct kvm_ptdump_register { > + void *(*get_ptdump_info)(struct kvm_ptdump_register *reg); > + void (*put_ptdump_info)(void *priv); > + int (*show_ptdump_info)(struct seq_file *m, void *v); > + void *priv; > +}; > + > +static int kvm_ptdump_open(struct inode *inode, struct file *file); > +static int kvm_ptdump_release(struct inode *inode, struct file *file); > +static int kvm_ptdump_show(struct seq_file *m, void *); > + > +static const struct file_operations kvm_ptdump_fops = { > + .open = kvm_ptdump_open, > + .read = seq_read, > + .llseek = seq_lseek, > + .release = kvm_ptdump_release, > +}; > + > +static int kvm_ptdump_open(struct inode *inode, struct file *file) > +{ > + struct kvm_ptdump_register *reg = inode->i_private; > + void *info = NULL; > + int ret; > + > + if (reg->get_ptdump_info) { > + info = reg->get_ptdump_info(reg); > + if (!info) > + return -ENOMEM; > + } > + > + if (!reg->show_ptdump_info) > + reg->show_ptdump_info = kvm_ptdump_show; > + > + ret = single_open(file, reg->show_ptdump_info, info); > + if (ret && reg->put_ptdump_info) > + reg->put_ptdump_info(info); > + > + return ret; > +} > + > +static int kvm_ptdump_release(struct inode *inode, struct file *file) > +{ > + struct kvm_ptdump_register *reg = inode->i_private; > + struct seq_file *seq_file = file->private_data; > + > + if (reg->put_ptdump_info) > + reg->put_ptdump_info(seq_file->private); > + Call single_release here.
> + return 0; > +} > + > +static int kvm_ptdump_show(struct seq_file *m, void *) > +{ > + return -EINVAL; > +} > + > +static void kvm_ptdump_debugfs_register(struct kvm_ptdump_register *reg, > + const char *name, struct dentry *parent) > +{ > + debugfs_create_file(name, 0400, parent, reg, &kvm_ptdump_fops); > +} > + > +static struct kvm_ptdump_register host_reg; > + > +void kvm_ptdump_register_host(void) > +{ > + if (!is_protected_kvm_enabled()) > + return; > + > + kvm_ptdump_debugfs_register(&host_reg, "host_page_tables", > + kvm_debugfs_dir); > +} > + > +static int __init kvm_host_ptdump_init(void) > +{ > + host_reg.priv = (void *)host_s2_pgtable_pages(); > + return 0; > +} > + > +device_initcall(kvm_host_ptdump_init); > -- > 2.43.0.472.g3155946c3a-goog >
| ![\](/images/icornerr.gif) |