[PATCH 3/3] x86/xen: Remove Xen debugfs support

[Juergen Gross <jgross@xxxxxxxx>]

The only Xen file in debugfs is for dumping the p2m table when running
as a Xen PV guest. This might have been useful when the PV code was
young, but there haven't been any p2m related bugs requiring the p2m
dump since ages.

Remove the code and the related config option.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
Kind of RFC, as there might be different opinions. The only time I
have used the p2m dump was when I reworked the p2m coding more than
10 years ago.
An alternative would be to make CONFIG_XEN_DEBUG_FS dependant on
CONFIG_XEN_PV and to fix the help text (it is completely wrong, as
it enables neither statistics output, nor tuning options, nor is it
relevant to performance at all - the only existing functionality
isn't mentioned either).

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 arch/x86/xen/Kconfig   |  7 -------
 arch/x86/xen/Makefile  |  2 --
 arch/x86/xen/debugfs.c | 16 ---------------
 arch/x86/xen/p2m.c     | 45 ------------------------------------------
 arch/x86/xen/xen-ops.h |  2 --
 5 files changed, 72 deletions(-)
 delete mode 100644 arch/x86/xen/debugfs.c

diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index aa4040fd9215..51b53ce66efb 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -65,13 +65,6 @@ config XEN_PVHVM_GUEST
        help
          Support running as a Xen PVHVM guest.
 
-config XEN_DEBUG_FS
-       bool "Enable Xen debug and tuning parameters in debugfs"
-       depends on XEN && DEBUG_FS
-       help
-         Enable statistics output and various tuning options in debugfs.
-         Enabling this option may incur a significant performance overhead.
-
 config XEN_PVH
        bool "Xen PVH guest support"
        depends on XEN && XEN_PVHVM && ACPI
diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index a9ec8c9f5c5d..717264ae269b 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -43,8 +43,6 @@ obj-$(CONFIG_XEN_PVHVM_SMP)   += smp_hvm.o
 
 obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
 
-obj-$(CONFIG_XEN_DEBUG_FS)     += debugfs.o
-
 obj-$(CONFIG_XEN_DOM0)         += vga.o
 
 obj-$(CONFIG_XEN_EFI)          += efi.o
diff --git a/arch/x86/xen/debugfs.c b/arch/x86/xen/debugfs.c
deleted file mode 100644
index b8c9f2a7d9b6..000000000000
--- a/arch/x86/xen/debugfs.c
+++ /dev/null
@@ -1,16 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <linux/init.h>
-#include <linux/debugfs.h>
-#include <linux/slab.h>
-
-#include "xen-ops.h"
-
-static struct dentry *d_xen_debug;
-
-struct dentry * __init xen_init_debugfs(void)
-{
-       if (!d_xen_debug)
-               d_xen_debug = debugfs_create_dir("xen", NULL);
-       return d_xen_debug;
-}
-
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 2dd12b61a230..d007ccf6e7a1 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -883,48 +883,3 @@ void __init xen_add_remap_nonram(phys_addr_t maddr, 
phys_addr_t paddr,
 
        nr_nonram_remap++;
 }
-
-#ifdef CONFIG_XEN_DEBUG_FS
-#include <linux/debugfs.h>
-static int p2m_dump_show(struct seq_file *m, void *v)
-{
-       static const char * const type_name[] = {
-                               [P2M_TYPE_IDENTITY] = "identity",
-                               [P2M_TYPE_MISSING] = "missing",
-                               [P2M_TYPE_PFN] = "pfn",
-                               [P2M_TYPE_UNKNOWN] = "abnormal"};
-       unsigned long pfn, first_pfn;
-       int type, prev_type;
-
-       prev_type = xen_p2m_elem_type(0);
-       first_pfn = 0;
-
-       for (pfn = 0; pfn < xen_p2m_size; pfn++) {
-               type = xen_p2m_elem_type(pfn);
-               if (type != prev_type) {
-                       seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
-                                  type_name[prev_type]);
-                       prev_type = type;
-                       first_pfn = pfn;
-               }
-       }
-       seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
-                  type_name[prev_type]);
-       return 0;
-}
-
-DEFINE_SHOW_ATTRIBUTE(p2m_dump);
-
-static struct dentry *d_mmu_debug;
-
-static int __init xen_p2m_debugfs(void)
-{
-       struct dentry *d_xen = xen_init_debugfs();
-
-       d_mmu_debug = debugfs_create_dir("mmu", d_xen);
-
-       debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
-       return 0;
-}
-fs_initcall(xen_p2m_debugfs);
-#endif /* CONFIG_XEN_DEBUG_FS */
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index a27ab1f50cf9..6808010ac379 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -254,8 +254,6 @@ static inline void xen_hvm_post_suspend(int 
suspend_cancelled) {}
 
 void xen_add_extra_mem(unsigned long start_pfn, unsigned long n_pfns);
 
-struct dentry * __init xen_init_debugfs(void);
-
 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
 void xen_hvm_init_mmu_ops(void);
 
-- 
2.54.0