linux/arch/x86
David Woodhouse 7a36d68065 KVM: x86/xen: fix recursive deadlock in timer injection
The fast-path timer delivery introduced a recursive locking deadlock
when userspace configures a timer which has already expired and is
delivered immediately. The call to kvm_xen_inject_timer_irqs() can
call to kvm_xen_set_evtchn() which may take kvm->arch.xen.xen_lock,
which is already held in kvm_xen_vcpu_get_attr().

 ============================================
 WARNING: possible recursive locking detected
 6.8.0-smp--5e10b4d51d77-drs #232 Tainted: G           O
 --------------------------------------------
 xen_shinfo_test/250013 is trying to acquire lock:
 ffff938c9930cc30 (&kvm->arch.xen.xen_lock){+.+.}-{3:3}, at: kvm_xen_set_evtchn+0x74/0x170 [kvm]

 but task is already holding lock:
 ffff938c9930cc30 (&kvm->arch.xen.xen_lock){+.+.}-{3:3}, at: kvm_xen_vcpu_get_attr+0x38/0x250 [kvm]

Now that the gfn_to_pfn_cache has its own self-sufficient locking, its
callers no longer need to ensure serialization, so just stop taking
kvm->arch.xen.xen_lock from kvm_xen_set_evtchn().

Fixes: 77c9b9dea4 ("KVM: x86/xen: Use fast path for Xen timer delivery")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Link: https://lore.kernel.org/r/20240227115648.3104-6-dwmw2@infradead.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-03-04 16:22:39 -08:00
..
boot x86/cleanups changes for v6.8: 2024-01-08 17:23:32 -08:00
coco - Add support managing TDX host hardware 2024-01-18 13:41:48 -08:00
configs
crypto This update includes the following changes: 2024-01-10 12:23:43 -08:00
entry asm-generic cleanups for 6.8 2024-01-10 18:13:44 -08:00
events Performance events changes for v6.8 are: 2024-01-08 19:37:20 -08:00
hyperv x86/cleanups changes for v6.8: 2024-01-08 17:23:32 -08:00
ia32
include KVM: x86/xen: allow vcpu_info to be mapped by fixed HVA 2024-02-22 07:01:17 -08:00
kernel x86 guest: 2024-02-07 17:52:16 +00:00
kvm KVM: x86/xen: fix recursive deadlock in timer injection 2024-03-04 16:22:39 -08:00
lib header cleanups for 6.8 2024-01-10 16:43:55 -08:00
math-emu
mm Many singleton patches against the MM code. The patch series which 2024-01-09 11:18:47 -08:00
net Networking changes for 6.8. 2024-01-11 10:07:29 -08:00
pci pci-v6.8-changes 2024-01-17 16:23:17 -08:00
platform x86/cleanups changes for v6.8: 2024-01-08 17:23:32 -08:00
power
purgatory
ras
realmode x86/cleanups changes for v6.8: 2024-01-08 17:23:32 -08:00
tools x86/build changes for v6.8: 2024-01-08 17:22:02 -08:00
um This pull request contains the following changes for UML: 2024-01-17 10:44:34 -08:00
video
virt
xen x86/cleanups changes for v6.8: 2024-01-08 17:23:32 -08:00
.gitignore
Kbuild
Kconfig IOMMU Updates for Linux v6.8 2024-01-18 15:16:57 -08:00
Kconfig.assembler
Kconfig.cpu
Kconfig.debug
Makefile kbuild: Replace tabs with spaces when followed by conditionals 2024-01-31 23:24:27 +09:00
Makefile_32.cpu
Makefile.postlink
Makefile.um