On 20.03.15 10:39, Paul Mackerras wrote:
> This creates a debugfs directory for each HV guest (assuming debugfs
> is enabled in the kernel config), and within that directory, a file
> by which the contents of the guest's HPT (hashed page table) can be
> read. The directory is named vmnnnn, where nnnn is the PID of the
> process that created the guest. The file is named "htab". This is
> intended to help in debugging problems in the host's management
> of guest memory.
>
> The contents of the file consist of a series of lines like this:
>
> 3f48 4000d032bf003505 0000000bd7ff1196 00000003b5c71196
>
> The first field is the index of the entry in the HPT, the second and
> third are the HPT entry, so the third entry contains the real page
> number that is mapped by the entry if the entry's valid bit is set.
> The fourth field is the guest's view of the second doubleword of the
> entry, so it contains the guest physical address. (The format of the
> second through fourth fields are described in the Power ISA and also
> in arch/powerpc/include/asm/mmu-hash64.h.)
>
> Signed-off-by: Paul Mackerras <pau...@samba.org>
> ---
> arch/powerpc/include/asm/kvm_book3s_64.h | 2 +
> arch/powerpc/include/asm/kvm_host.h | 2 +
> arch/powerpc/kvm/book3s_64_mmu_hv.c | 136
> +++++++++++++++++++++++++++++++
> arch/powerpc/kvm/book3s_hv.c | 12 +++
> virt/kvm/kvm_main.c | 1 +
> 5 files changed, 153 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h
> b/arch/powerpc/include/asm/kvm_book3s_64.h
> index 0789a0f..869c53f 100644
> --- a/arch/powerpc/include/asm/kvm_book3s_64.h
> +++ b/arch/powerpc/include/asm/kvm_book3s_64.h
> @@ -436,6 +436,8 @@ static inline struct kvm_memslots
> *kvm_memslots_raw(struct kvm *kvm)
> return rcu_dereference_raw_notrace(kvm->memslots);
> }
>
> +extern void kvmppc_mmu_debugfs_init(struct kvm *kvm);
> +
> #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
>
> #endif /* __ASM_KVM_BOOK3S_64_H__ */
> diff --git a/arch/powerpc/include/asm/kvm_host.h
> b/arch/powerpc/include/asm/kvm_host.h
> index 015773f..f1d0bbc 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -238,6 +238,8 @@ struct kvm_arch {
> atomic_t hpte_mod_interest;
> cpumask_t need_tlb_flush;
> int hpt_cma_alloc;
> + struct dentry *debugfs_dir;
> + struct dentry *htab_dentry;
> #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
> #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
> struct mutex hpt_mutex;
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> index 6c6825a..d6fe308 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> @@ -27,6 +27,7 @@
> #include <linux/srcu.h>
> #include <linux/anon_inodes.h>
> #include <linux/file.h>
> +#include <linux/debugfs.h>
>
> #include <asm/tlbflush.h>
> #include <asm/kvm_ppc.h>
> @@ -1490,6 +1491,141 @@ int kvm_vm_ioctl_get_htab_fd(struct kvm *kvm, struct
> kvm_get_htab_fd *ghf)
> return ret;
> }
>
> +struct debugfs_htab_state {
> + struct kvm *kvm;
> + struct mutex mutex;
> + unsigned long hpt_index;
> + int chars_left;
> + int buf_index;
> + char buf[64];
> +};
> +
> +static int debugfs_htab_open(struct inode *inode, struct file *file)
> +{
> + struct kvm *kvm = inode->i_private;
> + struct debugfs_htab_state *p;
> +
> + p = kzalloc(sizeof(*p), GFP_KERNEL);
> + if (!p)
> + return -ENOMEM;
> +
> + kvm_get_kvm(kvm);
> + p->kvm = kvm;
> + mutex_init(&p->mutex);
> + file->private_data = p;
> +
> + return nonseekable_open(inode, file);
> +}
> +
> +static int debugfs_htab_release(struct inode *inode, struct file *file)
> +{
> + struct debugfs_htab_state *p = file->private_data;
> +
> + kvm_put_kvm(p->kvm);
> + kfree(p);
> + return 0;
> +}
> +
> +static ssize_t debugfs_htab_read(struct file *file, char __user *buf,
> + size_t len, loff_t *ppos)
> +{
> + struct debugfs_htab_state *p = file->private_data;
> + ssize_t ret, r;
> + unsigned long i, n;
> + unsigned long v, hr, gr;
> + struct kvm *kvm;
> + __be64 *hptp;
> +
> + ret = mutex_lock_interruptible(&p->mutex);
> + if (ret)
> + return ret;
> +
> + if (p->chars_left) {
> + n = p->chars_left;
> + if (n > len)
> + n = len;
> + r = copy_to_user(buf, p->buf + p->buf_index, n);
> + n -= r;
> + p->chars_left -= n;
> + p->buf_index += n;
> + buf += n;
> + len -= n;
> + ret = n;
> + if (r) {
> + if (!n)
> + ret = -EFAULT;
> + goto out;
> + }
> + }
> +
> + kvm = p->kvm;
> + i = p->hpt_index;
> + hptp = (__be64 *)(kvm->arch.hpt_virt + (i * HPTE_SIZE));
> + for (; len != 0 && i < kvm->arch.hpt_npte; ++i, hptp += 2) {
> + if (!(be64_to_cpu(hptp[0]) & (HPTE_V_VALID | HPTE_V_ABSENT)))
> + continue;
> +
> + /* lock the HPTE so it's stable and read it */
> + preempt_disable();
> + while (!try_lock_hpte(hptp, HPTE_V_HVLOCK))
> + cpu_relax();
> + v = be64_to_cpu(hptp[0]) & ~HPTE_V_HVLOCK;
> + hr = be64_to_cpu(hptp[1]);
> + gr = kvm->arch.revmap[i].guest_rpte;
> + unlock_hpte(hptp, v);
> + preempt_enable();
> +
> + if (!(v & (HPTE_V_VALID | HPTE_V_ABSENT)))
> + continue;
> +
> + n = scnprintf(p->buf, sizeof(p->buf),
> + "%6lx %.16lx %.16lx %.16lx\n",
> + i, v, hr, gr);
> + p->chars_left = n;
> + if (n > len)
> + n = len;
> + r = copy_to_user(buf, p->buf, n);
> + n -= r;
> + p->chars_left -= n;
> + p->buf_index = n;
> + buf += n;
> + len -= n;
> + ret += n;
> + if (r) {
> + if (!ret)
> + ret = -EFAULT;
> + goto out;
> + }
> + }
> + p->hpt_index = i;
> +
> + out:
> + mutex_unlock(&p->mutex);
> + return ret;
> +}
> +
> +ssize_t debugfs_htab_write(struct file *file, const char __user *buf,
> + size_t len, loff_t *ppos)
> +{
> + return -EACCES;
> +}
> +
> +static const struct file_operations debugfs_htab_fops = {
> + .owner = THIS_MODULE,
> + .open = debugfs_htab_open,
> + .release = debugfs_htab_release,
> + .read = debugfs_htab_read,
> + .write = debugfs_htab_write,
> + .llseek = generic_file_llseek,
> +};
> +
> +void kvmppc_mmu_debugfs_init(struct kvm *kvm)
> +{
> + kvm->arch.htab_dentry = debugfs_create_file("htab", 0400,
> + kvm->arch.debugfs_dir, kvm,
> + &debugfs_htab_fops);
> +}
> +
> void kvmppc_mmu_book3s_hv_init(struct kvm_vcpu *vcpu)
> {
> struct kvmppc_mmu *mmu = &vcpu->arch.mmu;
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 7b7102a..6631b53 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -32,6 +32,7 @@
> #include <linux/page-flags.h>
> #include <linux/srcu.h>
> #include <linux/miscdevice.h>
> +#include <linux/debugfs.h>
>
> #include <asm/reg.h>
> #include <asm/cputable.h>
> @@ -2307,6 +2308,7 @@ static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu
> *vcpu)
> static int kvmppc_core_init_vm_hv(struct kvm *kvm)
> {
> unsigned long lpcr, lpid;
> + char buf[32];
>
> /* Allocate the guest's logical partition ID */
>
> @@ -2347,6 +2349,14 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
> */
> kvm_hv_vm_activated();
>
> + /*
> + * Create a debugfs directory for the VM
> + */
> + sprintf(buf, "vm%d", current->pid);
The same comment stands here. I don't see how you could possibly overrun
32 bytes with vm%d, but I'd feel a lot safer if this was an snprintf.
Alex
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