On 06.09.21 23:35, Sander Eikelenboom wrote:
L.S.,On my AMD box running: xen-unstable changeset: Fri Sep 3 15:10:43 2021 +0200 git:2d4978ead4 linux kernel: 5.14.1 With this setup I'm encountering some issues in dom0, see below.
Could you test whether the attached patch (only compile tested) fixes the issue for you? Juergen
From c9e4ce85bcb9003ffa4877743e1792ac6ec24f19 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgr...@suse.com>
To: x...@kernel.org
To: linux-ker...@vger.kernel.org
Cc: Boris Ostrovsky <boris.ostrov...@oracle.com>
Cc: Juergen Gross <jgr...@suse.com>
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Borislav Petkov <b...@alien8.de>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: xen-devel@lists.xenproject.org
Date: Tue, 7 Sep 2021 15:17:39 +0200
Subject: [PATCH] xen: fix usage of pmd/pud_poplulate in mremap for pv guests
Commit 0881ace292b662 ("mm/mremap: use pmd/pud_poplulate to update page
table entries") introduced a regression when running as Xen PV guest.
Today pmd/pud_poplulate() for Xen PV assumes that the PFN inserted is
referencing a not yet used page table. In case of move_normal_pmd/pud()
this is not true, resulting in WARN splats like:
[34321.304270] ------------[ cut here ]------------
[34321.304277] WARNING: CPU: 0 PID: 23628 at arch/x86/xen/multicalls.c:102 xen_mc_flush+0x176/0x1a0
[34321.304288] Modules linked in:
[34321.304291] CPU: 0 PID: 23628 Comm: apt-get Not tainted 5.14.1-20210906-doflr-mac80211debug+ #1
[34321.304294] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS V1.8B1 09/13/2010
[34321.304296] RIP: e030:xen_mc_flush+0x176/0x1a0
[34321.304300] Code: 89 45 18 48 c1 e9 3f 48 89 ce e9 20 ff ff ff e8 60 03 00 00 66 90 5b 5d 41 5c 41 5d c3 48 c7 45 18 ea ff ff ff be 01 00 00 00 <0f> 0b 8b 55 00 48 c7 c7 10 97 aa 82 31 db 49 c7 c5 38 97 aa 82 65
[34321.304303] RSP: e02b:ffffc90000a97c90 EFLAGS: 00010002
[34321.304305] RAX: ffff88807d416398 RBX: ffff88807d416350 RCX: ffff88807d416398
[34321.304306] RDX: 0000000000000001 RSI: 0000000000000001 RDI: deadbeefdeadf00d
[34321.304308] RBP: ffff88807d416300 R08: aaaaaaaaaaaaaaaa R09: ffff888006160cc0
[34321.304309] R10: deadbeefdeadf00d R11: ffffea000026a600 R12: 0000000000000000
[34321.304310] R13: ffff888012f6b000 R14: 0000000012f6b000 R15: 0000000000000001
[34321.304320] FS: 00007f5071177800(0000) GS:ffff88807d400000(0000) knlGS:0000000000000000
[34321.304322] CS: 10000e030 DS: 0000 ES: 0000 CR0: 0000000080050033
[34321.304323] CR2: 00007f506f542000 CR3: 00000000160cc000 CR4: 0000000000000660
[34321.304326] Call Trace:
[34321.304331] xen_alloc_pte+0x294/0x320
[34321.304334] move_pgt_entry+0x165/0x4b0
[34321.304339] move_page_tables+0x6fa/0x8d0
[34321.304342] move_vma.isra.44+0x138/0x500
[34321.304345] __x64_sys_mremap+0x296/0x410
[34321.304348] do_syscall_64+0x3a/0x80
[34321.304352] entry_SYSCALL_64_after_hwframe+0x44/0xae
[34321.304355] RIP: 0033:0x7f507196301a
[34321.304358] Code: 73 01 c3 48 8b 0d 76 0e 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 19 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 46 0e 0c 00 f7 d8 64 89 01 48
[34321.304360] RSP: 002b:00007ffda1eecd38 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
[34321.304362] RAX: ffffffffffffffda RBX: 000056205f950f30 RCX: 00007f507196301a
[34321.304363] RDX: 0000000001a00000 RSI: 0000000001900000 RDI: 00007f506dc56000
[34321.304364] RBP: 0000000001a00000 R08: 0000000000000010 R09: 0000000000000004
[34321.304365] R10: 0000000000000001 R11: 0000000000000246 R12: 00007f506dc56060
[34321.304367] R13: 00007f506dc56000 R14: 00007f506dc56060 R15: 000056205f950f30
[34321.304368] ---[ end trace a19885b78fe8f33e ]---
[34321.304370] 1 of 2 multicall(s) failed: cpu 0
[34321.304371] call 2: op=12297829382473034410 arg=[aaaaaaaaaaaaaaaa] result=-22
Fix that by modifying xen_alloc_ptpage() to only pin the page table in
case it wasn't pinned already.
Fixes: 0881ace292b662 ("mm/mremap: use pmd/pud_poplulate to update page table entries")
Cc: <sta...@vger.kernel.org>
Reported-by: Sander Eikelenboom <li...@eikelenboom.it>
Signed-off-by: Juergen Gross <jgr...@suse.com>
---
arch/x86/xen/mmu_pv.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 1df5f01529e5..8d751939c6f3 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1518,14 +1518,17 @@ static inline void xen_alloc_ptpage(struct mm_struct *mm, unsigned long pfn,
if (pinned) {
struct page *page = pfn_to_page(pfn);
- if (static_branch_likely(&xen_struct_pages_ready))
+ pinned = false;
+ if (static_branch_likely(&xen_struct_pages_ready)) {
+ pinned = PagePinned(page);
SetPagePinned(page);
+ }
xen_mc_batch();
__set_pfn_prot(pfn, PAGE_KERNEL_RO);
- if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS)
+ if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS && !pinned)
__pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
xen_mc_issue(PARAVIRT_LAZY_MMU);
--
2.26.2
OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key
OpenPGP_signature
Description: OpenPGP digital signature
