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authorWeinan Li <weinan.z.li@intel.com>2018-09-17 09:46:14 +0800
committerZhenyu Wang <zhenyuw@linux.intel.com>2018-09-18 10:37:55 +0800
commita1ac5f0943019bfd76345fe05a42cbc400da685c (patch)
treef373dd19a26492d7c03eca6a6074db7b0c49272c /drivers/gpu
parentd817de3bc186c305b8e72a52547df2971c06499d (diff)
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')
-rw-r--r--drivers/gpu/drm/i915/gvt/kvmgt.c7
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 = {