[PATCH] Revert "xen: add helpers to allocate unpopulated memory"

From: Marek Marczykowski-Górecki
Date: Sun Dec 06 2020 - 12:25:11 EST

This reverts commit 9e2369c06c8a181478039258a4598c1ddd2cadfa.

On a Xen PV dom0, with NVME disk, this makes the dom0 crash when starting
a domain. This looks like some bad interaction between xen-blkback and
NVME driver, both using ZONE_DEVICE. Since the author is on leave now,
revert the change until proper solution is developed.

The specific crash message is:

general protection fault, probably for non-canonical address 0xdead000000000100: 0000 [#1] SMP NOPTI
CPU: 1 PID: 134 Comm: kworker/u12:2 Not tainted 5.9.9-1.qubes.x86_64 #1
Hardware name: LENOVO 20M9CTO1WW/20M9CTO1WW, BIOS N2CET50W (1.33 ) 01/15/2020
Workqueue: dm-thin do_worker [dm_thin_pool]
RIP: e030:nvme_map_data+0x300/0x3a0 [nvme]
Code: b8 fe ff ff e9 a8 fe ff ff 4c 8b 56 68 8b 5e 70 8b 76 74 49 8b 02 48 c1 e8 33 83 e0 07 83 f8 04 0f 85 f2 fe ff ff 49 8b 42 08 <83> b8 d0 00 00 00 04 0f 85 e1 fe ff ff e9 38 fd ff ff 8b 55 70 be
RSP: e02b:ffffc900010e7ad8 EFLAGS: 00010246
RAX: dead000000000100 RBX: 0000000000001000 RCX: ffff8881a58f5000
RDX: 0000000000001000 RSI: 0000000000000000 RDI: ffff8881a679e000
RBP: ffff8881a5ef4c80 R08: ffff8881a5ef4c80 R09: 0000000000000002
R10: ffffea0003dfff40 R11: 0000000000000008 R12: ffff8881a679e000
R13: ffffc900010e7b20 R14: ffff8881a70b5980 R15: ffff8881a679e000
FS: 0000000000000000(0000) GS:ffff8881b5440000(0000) knlGS:0000000000000000
CS: e030 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001d64408 CR3: 00000001aa2c0000 CR4: 0000000000050660
Call Trace:
nvme_queue_rq+0xa7/0x1a0 [nvme]
__blk_mq_try_issue_directly+0x11d/0x1e0
? add_wait_queue_exclusive+0x70/0x70
blk_mq_try_issue_directly+0x35/0xc0l[
blk_mq_submit_bio+0x58f/0x660
__submit_bio_noacct+0x300/0x330
process_shared_bio+0x126/0x1b0 [dm_thin_pool]
process_cell+0x226/0x280 [dm_thin_pool]
process_thin_deferred_cells+0x185/0x320 [dm_thin_pool]
process_deferred_bios+0xa4/0x2a0 [dm_thin_pool]UX
do_worker+0xcc/0x130 [dm_thin_pool]
process_one_work+0x1b4/0x370
worker_thread+0x4c/0x310
? process_one_work+0x370/0x370
kthread+0x11b/0x140
? __kthread_bind_mask+0x60/0x60<
ret_from_fork+0x22/0x30
Modules linked in: loop snd_seq_dummy snd_hrtimer nf_tables nfnetlink vfat fat snd_sof_pci snd_sof_intel_byt snd_sof_intel_ipc snd_sof_intel_hda_common snd_soc_hdac_hda snd_sof_xtensa_dsp snd_sof_intel_hda snd_sof snd_soc_skl snd_soc_sst_
ipc snd_soc_sst_dsp snd_hda_ext_core snd_soc_acpi_intel_match snd_soc_acpi snd_soc_core snd_compress ac97_bus snd_pcm_dmaengine elan_i2c snd_hda_codec_hdmi mei_hdcp iTCO_wdt intel_powerclamp intel_pmc_bxt ee1004 intel_rapl_msr iTCO_vendor
_support joydev pcspkr intel_wmi_thunderbolt wmi_bmof thunderbolt ucsi_acpi idma64 typec_ucsi snd_hda_codec_realtek typec snd_hda_codec_generic snd_hda_intel snd_intel_dspcfg snd_hda_codec thinkpad_acpi snd_hda_core ledtrig_audio int3403_
thermal snd_hwdep snd_seq snd_seq_device snd_pcm iwlwifi snd_timer processor_thermal_device mei_me cfg80211 intel_rapl_common snd e1000e mei int3400_thermal int340x_thermal_zone i2c_i801 acpi_thermal_rel soundcore intel_soc_dts_iosf i2c_s
mbus rfkill intel_pch_thermal xenfs
ip_tables dm_thin_pool dm_persistent_data dm_bio_prison dm_crypt nouveau rtsx_pci_sdmmc mmc_core mxm_wmi crct10dif_pclmul ttm crc32_pclmul crc32c_intel i915 ghash_clmulni_intel i2c_algo_bit serio_raw nvme drm_kms_helper cec xhci_pci nvme
_core rtsx_pci xhci_pci_renesas drm xhci_hcd wmi video pinctrl_cannonlake pinctrl_intel xen_privcmd xen_pciback xen_blkback xen_gntalloc xen_gntdev xen_evtchn uinput
---[ end trace f8d47e4aa6724df4 ]---
RIP: e030:nvme_map_data+0x300/0x3a0 [nvme]
Code: b8 fe ff ff e9 a8 fe ff ff 4c 8b 56 68 8b 5e 70 8b 76 74 49 8b 02 48 c1 e8 33 83 e0 07 83 f8 04 0f 85 f2 fe ff ff 49 8b 42 08 <83> b8 d0 00 00 00 04 0f 85 e1 fe ff ff e9 38 fd ff ff 8b 55 70 be
RSP: e02b:ffffc900010e7ad8 EFLAGS: 00010246
RAX: dead000000000100 RBX: 0000000000001000 RCX: ffff8881a58f5000
RDX: 0000000000001000 RSI: 0000000000000000 RDI: ffff8881a679e000
RBP: ffff8881a5ef4c80 R08: ffff8881a5ef4c80 R09: 0000000000000002
R10: ffffea0003dfff40 R11: 0000000000000008 R12: ffff8881a679e000
R13: ffffc900010e7b20 R14: ffff8881a70b5980 R15: ffff8881a679e000
FS: 0000000000000000(0000) GS:ffff8881b5440000(0000) knlGS:0000000000000000
CS: e030 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001d64408 CR3: 00000001aa2c0000 CR4: 0000000000050660
Kernel panic - not syncing: Fatal exception
Kernel Offset: disabled

Discussion at https://lore.kernel.org/xen-devel/20201205082839.ts3ju6yta46cgwjn@Air-de-Roger/T

Cc: stable@xxxxxxxxxxxxxxx #v5.9+
(for 5.9 it's easier to revert the original commit directly)
Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/xen/xen_drm_front_gem.c | 9 +-
drivers/xen/Kconfig | 10 --
drivers/xen/Makefile | 1 -
drivers/xen/balloon.c | 4 +-
drivers/xen/grant-table.c | 4 +-
drivers/xen/privcmd.c | 4 +-
drivers/xen/unpopulated-alloc.c | 200 ------------------------
drivers/xen/xenbus/xenbus_client.c | 6 +-
drivers/xen/xlate_mmu.c | 4 +-
include/xen/xen.h | 9 --
10 files changed, 15 insertions(+), 236 deletions(-)
delete mode 100644 drivers/xen/unpopulated-alloc.c

diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/xen/xen_drm_front_gem.c
index 2f464ef2d53e..90945344daae 100644
--- a/drivers/gpu/drm/xen/xen_drm_front_gem.c
+++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
@@ -18,7 +18,6 @@
#include <drm/drm_probe_helper.h>

#include <xen/balloon.h>
-#include <xen/xen.h>

#include "xen_drm_front.h"
#include "xen_drm_front_gem.h"
@@ -100,8 +99,8 @@ static struct xen_gem_object *gem_create(struct drm_device *dev, size_t size)
* allocate ballooned pages which will be used to map
* grant references provided by the backend
*/
- ret = xen_alloc_unpopulated_pages(xen_obj->num_pages,
- xen_obj->pages);
+ ret = alloc_xenballooned_pages(xen_obj->num_pages,
+ xen_obj->pages);
if (ret < 0) {
DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n",
xen_obj->num_pages, ret);
@@ -153,8 +152,8 @@ void xen_drm_front_gem_free_object_unlocked(struct drm_gem_object *gem_obj)
} else {
if (xen_obj->pages) {
if (xen_obj->be_alloc) {
- xen_free_unpopulated_pages(xen_obj->num_pages,
- xen_obj->pages);
+ free_xenballooned_pages(xen_obj->num_pages,
+ xen_obj->pages);
gem_free_pages_array(xen_obj);
} else {
drm_gem_put_pages(&xen_obj->base,
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 41645fe6ad48..ea6c1e7e3e42 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -325,14 +325,4 @@ config XEN_HAVE_VPMU
config XEN_FRONT_PGDIR_SHBUF
tristate

-config XEN_UNPOPULATED_ALLOC
- bool "Use unpopulated memory ranges for guest mappings"
- depends on X86 && ZONE_DEVICE
- default XEN_BACKEND || XEN_GNTDEV || XEN_DOM0
- help
- Use unpopulated memory ranges in order to create mappings for guest
- memory regions, including grant maps and foreign pages. This avoids
- having to balloon out RAM regions in order to obtain physical memory
- space to create such mappings.
-
endmenu
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index babdca808861..c25c9a699b48 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -41,4 +41,3 @@ xen-gntdev-$(CONFIG_XEN_GNTDEV_DMABUF) += gntdev-dmabuf.o
xen-gntalloc-y := gntalloc.o
xen-privcmd-y := privcmd.o privcmd-buf.o
obj-$(CONFIG_XEN_FRONT_PGDIR_SHBUF) += xen-front-pgdir-shbuf.o
-obj-$(CONFIG_XEN_UNPOPULATED_ALLOC) += unpopulated-alloc.o
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index b57b2067ecbf..12d3a95bfdb4 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -653,7 +653,7 @@ void free_xenballooned_pages(int nr_pages, struct page **pages)
}
EXPORT_SYMBOL(free_xenballooned_pages);

-#if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC)
+#ifdef CONFIG_XEN_PV
static void __init balloon_add_region(unsigned long start_pfn,
unsigned long pages)
{
@@ -707,7 +707,7 @@ static int __init balloon_init(void)
register_sysctl_table(xen_root);
#endif

-#if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC)
+#ifdef CONFIG_XEN_PV
{
int i;

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 523dcdf39cc9..8d06bf1cc347 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -801,7 +801,7 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
{
int ret;

- ret = xen_alloc_unpopulated_pages(nr_pages, pages);
+ ret = alloc_xenballooned_pages(nr_pages, pages);
if (ret < 0)
return ret;

@@ -836,7 +836,7 @@ EXPORT_SYMBOL_GPL(gnttab_pages_clear_private);
void gnttab_free_pages(int nr_pages, struct page **pages)
{
gnttab_pages_clear_private(nr_pages, pages);
- xen_free_unpopulated_pages(nr_pages, pages);
+ free_xenballooned_pages(nr_pages, pages);
}
EXPORT_SYMBOL_GPL(gnttab_free_pages);

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index b0c73c58f987..63abe6c3642b 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -424,7 +424,7 @@ static int alloc_empty_pages(struct vm_area_struct *vma, int numpgs)
if (pages == NULL)
return -ENOMEM;

- rc = xen_alloc_unpopulated_pages(numpgs, pages);
+ rc = alloc_xenballooned_pages(numpgs, pages);
if (rc != 0) {
pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__,
numpgs, rc);
@@ -895,7 +895,7 @@ static void privcmd_close(struct vm_area_struct *vma)

rc = xen_unmap_domain_gfn_range(vma, numgfns, pages);
if (rc == 0)
- xen_free_unpopulated_pages(numpgs, pages);
+ free_xenballooned_pages(numpgs, pages);
else
pr_crit("unable to unmap MFN range: leaking %d pages. rc=%d\n",
numpgs, rc);
diff --git a/drivers/xen/unpopulated-alloc.c b/drivers/xen/unpopulated-alloc.c
deleted file mode 100644
index 8c512ea550bb..000000000000
--- a/drivers/xen/unpopulated-alloc.c
+++ /dev/null
@@ -1,200 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <linux/errno.h>
-#include <linux/gfp.h>
-#include <linux/kernel.h>
-#include <linux/mm.h>
-#include <linux/memremap.h>
-#include <linux/slab.h>
-
-#include <asm/page.h>
-
-#include <xen/page.h>
-#include <xen/xen.h>
-
-static DEFINE_MUTEX(list_lock);
-static LIST_HEAD(page_list);
-static unsigned int list_count;
-
-static int fill_list(unsigned int nr_pages)
-{
- struct dev_pagemap *pgmap;
- struct resource *res;
- void *vaddr;
- unsigned int i, alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
- int ret = -ENOMEM;
-
- res = kzalloc(sizeof(*res), GFP_KERNEL);
- if (!res)
- return -ENOMEM;
-
- pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
- if (!pgmap)
- goto err_pgmap;
-
- pgmap->type = MEMORY_DEVICE_GENERIC;
- res->name = "Xen scratch";
- res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
-
- ret = allocate_resource(&iomem_resource, res,
- alloc_pages * PAGE_SIZE, 0, -1,
- PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
- if (ret < 0) {
- pr_err("Cannot allocate new IOMEM resource\n");
- goto err_resource;
- }
-
- pgmap->range = (struct range) {
- .start = res->start,
- .end = res->end,
- };
- pgmap->nr_range = 1;
- pgmap->owner = res;
-
-#ifdef CONFIG_XEN_HAVE_PVMMU
- /*
- * memremap will build page tables for the new memory so
- * the p2m must contain invalid entries so the correct
- * non-present PTEs will be written.
- *
- * If a failure occurs, the original (identity) p2m entries
- * are not restored since this region is now known not to
- * conflict with any devices.
- */
- if (!xen_feature(XENFEAT_auto_translated_physmap)) {
- xen_pfn_t pfn = PFN_DOWN(res->start);
-
- for (i = 0; i < alloc_pages; i++) {
- if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
- pr_warn("set_phys_to_machine() failed, no memory added\n");
- ret = -ENOMEM;
- goto err_memremap;
- }
- }
- }
-#endif
-
- vaddr = memremap_pages(pgmap, NUMA_NO_NODE);
- if (IS_ERR(vaddr)) {
- pr_err("Cannot remap memory range\n");
- ret = PTR_ERR(vaddr);
- goto err_memremap;
- }
-
- for (i = 0; i < alloc_pages; i++) {
- struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);
-
- BUG_ON(!virt_addr_valid(vaddr + PAGE_SIZE * i));
- list_add(&pg->lru, &page_list);
- list_count++;
- }
-
- return 0;
-
-err_memremap:
- release_resource(res);
-err_resource:
- kfree(pgmap);
-err_pgmap:
- kfree(res);
- return ret;
-}
-
-/**
- * xen_alloc_unpopulated_pages - alloc unpopulated pages
- * @nr_pages: Number of pages
- * @pages: pages returned
- * @return 0 on success, error otherwise
- */
-int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
-{
- unsigned int i;
- int ret = 0;
-
- mutex_lock(&list_lock);
- if (list_count < nr_pages) {
- ret = fill_list(nr_pages - list_count);
- if (ret)
- goto out;
- }
-
- for (i = 0; i < nr_pages; i++) {
- struct page *pg = list_first_entry_or_null(&page_list,
- struct page,
- lru);
-
- BUG_ON(!pg);
- list_del(&pg->lru);
- list_count--;
- pages[i] = pg;
-
-#ifdef CONFIG_XEN_HAVE_PVMMU
- if (!xen_feature(XENFEAT_auto_translated_physmap)) {
- ret = xen_alloc_p2m_entry(page_to_pfn(pg));
- if (ret < 0) {
- unsigned int j;
-
- for (j = 0; j <= i; j++) {
- list_add(&pages[j]->lru, &page_list);
- list_count++;
- }
- goto out;
- }
- }
-#endif
- }
-
-out:
- mutex_unlock(&list_lock);
- return ret;
-}
-EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
-
-/**
- * xen_free_unpopulated_pages - return unpopulated pages
- * @nr_pages: Number of pages
- * @pages: pages to return
- */
-void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
-{
- unsigned int i;
-
- mutex_lock(&list_lock);
- for (i = 0; i < nr_pages; i++) {
- list_add(&pages[i]->lru, &page_list);
- list_count++;
- }
- mutex_unlock(&list_lock);
-}
-EXPORT_SYMBOL(xen_free_unpopulated_pages);
-
-#ifdef CONFIG_XEN_PV
-static int __init init(void)
-{
- unsigned int i;
-
- if (!xen_domain())
- return -ENODEV;
-
- if (!xen_pv_domain())
- return 0;
-
- /*
- * Initialize with pages from the extra memory regions (see
- * arch/x86/xen/setup.c).
- */
- for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
- unsigned int j;
-
- for (j = 0; j < xen_extra_mem[i].n_pfns; j++) {
- struct page *pg =
- pfn_to_page(xen_extra_mem[i].start_pfn + j);
-
- list_add(&pg->lru, &page_list);
- list_count++;
- }
- }
-
- return 0;
-}
-subsys_initcall(init);
-#endif
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index fd80e318b99c..ef8b6ea8ecca 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -618,7 +618,7 @@ static int xenbus_map_ring_hvm(struct xenbus_device *dev,
bool leaked = false;
unsigned int nr_pages = XENBUS_PAGES(nr_grefs);

- err = xen_alloc_unpopulated_pages(nr_pages, node->hvm.pages);
+ err = alloc_xenballooned_pages(nr_pages, node->hvm.pages);
if (err)
goto out_err;

@@ -659,7 +659,7 @@ static int xenbus_map_ring_hvm(struct xenbus_device *dev,
addr, nr_pages);
out_free_ballooned_pages:
if (!leaked)
- xen_free_unpopulated_pages(nr_pages, node->hvm.pages);
+ free_xenballooned_pages(nr_pages, node->hvm.pages);
out_err:
return err;
}
@@ -860,7 +860,7 @@ static int xenbus_unmap_ring_hvm(struct xenbus_device *dev, void *vaddr)
info.addrs);
if (!rv) {
vunmap(vaddr);
- xen_free_unpopulated_pages(nr_pages, node->hvm.pages);
+ free_xenballooned_pages(nr_pages, node->hvm.pages);
}
else
WARN(1, "Leaking %p, size %u page(s)\n", vaddr, nr_pages);
diff --git a/drivers/xen/xlate_mmu.c b/drivers/xen/xlate_mmu.c
index 34742c6e189e..7b1077f0abcb 100644
--- a/drivers/xen/xlate_mmu.c
+++ b/drivers/xen/xlate_mmu.c
@@ -232,7 +232,7 @@ int __init xen_xlate_map_ballooned_pages(xen_pfn_t **gfns, void **virt,
kfree(pages);
return -ENOMEM;
}
- rc = xen_alloc_unpopulated_pages(nr_pages, pages);
+ rc = alloc_xenballooned_pages(nr_pages, pages);
if (rc) {
pr_warn("%s Couldn't balloon alloc %ld pages rc:%d\n", __func__,
nr_pages, rc);
@@ -249,7 +249,7 @@ int __init xen_xlate_map_ballooned_pages(xen_pfn_t **gfns, void **virt,
if (!vaddr) {
pr_warn("%s Couldn't map %ld pages rc:%d\n", __func__,
nr_pages, rc);
- xen_free_unpopulated_pages(nr_pages, pages);
+ free_xenballooned_pages(nr_pages, pages);
kfree(pages);
kfree(pfns);
return -ENOMEM;
diff --git a/include/xen/xen.h b/include/xen/xen.h
index 43efba045acc..19a72f591e2b 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -52,13 +52,4 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
extern u64 xen_saved_max_mem_size;
#endif

-#ifdef CONFIG_XEN_UNPOPULATED_ALLOC
-int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages);
-void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages);
-#else
-#define xen_alloc_unpopulated_pages alloc_xenballooned_pages
-#define xen_free_unpopulated_pages free_xenballooned_pages
-#include <xen/balloon.h>
-#endif
-
#endif /* _XEN_XEN_H */
--
2.25.4