diff options
| author | Weinan Li <weinan.z.li@intel.com> | 2018-09-17 09:46:14 +0800 |
|---|---|---|
| committer | Zhenyu Wang <zhenyuw@linux.intel.com> | 2018-09-18 10:37:55 +0800 |
| commit | a1ac5f0943019bfd76345fe05a42cbc400da685c (patch) | |
| tree | f373dd19a26492d7c03eca6a6074db7b0c49272c /drivers/gpu/drm | |
| parent | d817de3bc186c305b8e72a52547df2971c06499d (diff) | |
| download | lwn-a1ac5f0943019bfd76345fe05a42cbc400da685c.tar.gz lwn-a1ac5f0943019bfd76345fe05a42cbc400da685c.zip | |
drm/i915/gvt: request srcu_read_lock before checking if one gfn is valid
Fix the suspicious RCU usage issue in intel_vgpu_emulate_mmio_write.
Here need to request the srcu read lock of kvm->srcu before doing
gfn_to_memslot(). The detailed log is as below:
[ 218.710688] =============================
[ 218.710690] WARNING: suspicious RCU usage
[ 218.710693] 4.14.15-dd+ #314 Tainted: G U
[ 218.710695] -----------------------------
[ 218.710697] ./include/linux/kvm_host.h:575 suspicious rcu_dereference_check() usage!
[ 218.710699]
other info that might help us debug this:
[ 218.710702]
rcu_scheduler_active = 2, debug_locks = 1
[ 218.710704] 1 lock held by qemu-system-x86/2144:
[ 218.710706] #0: (&gvt->lock){+.+.}, at: [<ffffffff816a1eea>] intel_vgpu_emulate_mmio_write+0x5a/0x2d0
[ 218.710721]
stack backtrace:
[ 218.710724] CPU: 0 PID: 2144 Comm: qemu-system-x86 Tainted: G U 4.14.15-dd+ #314
[ 218.710727] Hardware name: Dell Inc. OptiPlex 7040/0Y7WYT, BIOS 1.1.1 10/07/2015
[ 218.710729] Call Trace:
[ 218.710734] dump_stack+0x7c/0xb3
[ 218.710739] gfn_to_memslot+0x15f/0x170
[ 218.710743] kvm_is_visible_gfn+0xa/0x30
[ 218.710746] intel_vgpu_emulate_gtt_mmio_write+0x267/0x3c0
[ 218.710751] ? __mutex_unlock_slowpath+0x3b/0x260
[ 218.710754] intel_vgpu_emulate_mmio_write+0x182/0x2d0
[ 218.710759] intel_vgpu_rw+0xba/0x170 [kvmgt]
[ 218.710763] intel_vgpu_write+0x14d/0x1a0 [kvmgt]
[ 218.710767] __vfs_write+0x23/0x130
[ 218.710770] vfs_write+0xb0/0x1b0
[ 218.710774] SyS_pwrite64+0x73/0x90
[ 218.710777] entry_SYSCALL_64_fastpath+0x25/0x9c
[ 218.710780] RIP: 0033:0x7f33e8a91da3
[ 218.710783] RSP: 002b:00007f33dddc8700 EFLAGS: 00000293
v2: add 'Fixes' tag, refine log format.(Zhenyu)
Fixes: cc753fbe1ac4 ("drm/i915/gvt: validate gfn before set shadow page")
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Weinan Li <weinan.z.li@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Diffstat (limited to 'drivers/gpu/drm')
| -rw-r--r-- | drivers/gpu/drm/i915/gvt/kvmgt.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c index c7afee37b2b8..9ad89e38f6c0 100644 --- a/drivers/gpu/drm/i915/gvt/kvmgt.c +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c @@ -1833,6 +1833,8 @@ static bool kvmgt_is_valid_gfn(unsigned long handle, unsigned long gfn) { struct kvmgt_guest_info *info; struct kvm *kvm; + int idx; + bool ret; if (!handle_valid(handle)) return false; @@ -1840,8 +1842,11 @@ static bool kvmgt_is_valid_gfn(unsigned long handle, unsigned long gfn) info = (struct kvmgt_guest_info *)handle; kvm = info->kvm; - return kvm_is_visible_gfn(kvm, gfn); + idx = srcu_read_lock(&kvm->srcu); + ret = kvm_is_visible_gfn(kvm, gfn); + srcu_read_unlock(&kvm->srcu, idx); + return ret; } struct intel_gvt_mpt kvmgt_mpt = { |