From a6ecfb11bf37743c1ac49b266595582b107b61d4 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 19 Mar 2019 12:47:11 +0000 Subject: KVM: arm/arm64: vgic-its: Take the srcu lock when writing to guest memory When halting a guest, QEMU flushes the virtual ITS caches, which amounts to writing to the various tables that the guest has allocated. When doing this, we fail to take the srcu lock, and the kernel shouts loudly if running a lockdep kernel: [ 69.680416] ============================= [ 69.680819] WARNING: suspicious RCU usage [ 69.681526] 5.1.0-rc1-00008-g600025238f51-dirty #18 Not tainted [ 69.682096] ----------------------------- [ 69.682501] ./include/linux/kvm_host.h:605 suspicious rcu_dereference_check() usage! [ 69.683225] [ 69.683225] other info that might help us debug this: [ 69.683225] [ 69.683975] [ 69.683975] rcu_scheduler_active = 2, debug_locks = 1 [ 69.684598] 6 locks held by qemu-system-aar/4097: [ 69.685059] #0: 0000000034196013 (&kvm->lock){+.+.}, at: vgic_its_set_attr+0x244/0x3a0 [ 69.686087] #1: 00000000f2ed935e (&its->its_lock){+.+.}, at: vgic_its_set_attr+0x250/0x3a0 [ 69.686919] #2: 000000005e71ea54 (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [ 69.687698] #3: 00000000c17e548d (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [ 69.688475] #4: 00000000ba386017 (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [ 69.689978] #5: 00000000c2c3c335 (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [ 69.690729] [ 69.690729] stack backtrace: [ 69.691151] CPU: 2 PID: 4097 Comm: qemu-system-aar Not tainted 5.1.0-rc1-00008-g600025238f51-dirty #18 [ 69.691984] Hardware name: rockchip evb_rk3399/evb_rk3399, BIOS 2019.04-rc3-00124-g2feec69fb1 03/15/2019 [ 69.692831] Call trace: [ 69.694072] lockdep_rcu_suspicious+0xcc/0x110 [ 69.694490] gfn_to_memslot+0x174/0x190 [ 69.694853] kvm_write_guest+0x50/0xb0 [ 69.695209] vgic_its_save_tables_v0+0x248/0x330 [ 69.695639] vgic_its_set_attr+0x298/0x3a0 [ 69.696024] kvm_device_ioctl_attr+0x9c/0xd8 [ 69.696424] kvm_device_ioctl+0x8c/0xf8 [ 69.696788] do_vfs_ioctl+0xc8/0x960 [ 69.697128] ksys_ioctl+0x8c/0xa0 [ 69.697445] __arm64_sys_ioctl+0x28/0x38 [ 69.697817] el0_svc_common+0xd8/0x138 [ 69.698173] el0_svc_handler+0x38/0x78 [ 69.698528] el0_svc+0x8/0xc The fix is to obviously take the srcu lock, just like we do on the read side of things since bf308242ab98. One wonders why this wasn't fixed at the same time, but hey... Fixes: bf308242ab98 ("KVM: arm/arm64: VGIC/ITS: protect kvm_read_guest() calls with SRCU lock") Signed-off-by: Marc Zyngier --- virt/kvm/arm/vgic/vgic-its.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'virt/kvm/arm/vgic/vgic-its.c') diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c index ab3f47745d9c..c41e11fd841c 100644 --- a/virt/kvm/arm/vgic/vgic-its.c +++ b/virt/kvm/arm/vgic/vgic-its.c @@ -1919,7 +1919,7 @@ static int vgic_its_save_ite(struct vgic_its *its, struct its_device *dev, ((u64)ite->irq->intid << KVM_ITS_ITE_PINTID_SHIFT) | ite->collection->collection_id; val = cpu_to_le64(val); - return kvm_write_guest(kvm, gpa, &val, ite_esz); + return kvm_write_guest_lock(kvm, gpa, &val, ite_esz); } /** @@ -2066,7 +2066,7 @@ static int vgic_its_save_dte(struct vgic_its *its, struct its_device *dev, (itt_addr_field << KVM_ITS_DTE_ITTADDR_SHIFT) | (dev->num_eventid_bits - 1)); val = cpu_to_le64(val); - return kvm_write_guest(kvm, ptr, &val, dte_esz); + return kvm_write_guest_lock(kvm, ptr, &val, dte_esz); } /** @@ -2246,7 +2246,7 @@ static int vgic_its_save_cte(struct vgic_its *its, ((u64)collection->target_addr << KVM_ITS_CTE_RDBASE_SHIFT) | collection->collection_id); val = cpu_to_le64(val); - return kvm_write_guest(its->dev->kvm, gpa, &val, esz); + return kvm_write_guest_lock(its->dev->kvm, gpa, &val, esz); } static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz) @@ -2317,7 +2317,7 @@ static int vgic_its_save_collection_table(struct vgic_its *its) */ val = 0; BUG_ON(cte_esz > sizeof(val)); - ret = kvm_write_guest(its->dev->kvm, gpa, &val, cte_esz); + ret = kvm_write_guest_lock(its->dev->kvm, gpa, &val, cte_esz); return ret; } -- cgit From 7494cec6cb3ba7385a6a223b81906384f15aae34 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 19 Mar 2019 12:56:23 +0000 Subject: KVM: arm/arm64: vgic-its: Take the srcu lock when parsing the memslots Calling kvm_is_visible_gfn() implies that we're parsing the memslots, and doing this without the srcu lock is frown upon: [12704.164532] ============================= [12704.164544] WARNING: suspicious RCU usage [12704.164560] 5.1.0-rc1-00008-g600025238f51-dirty #16 Tainted: G W [12704.164573] ----------------------------- [12704.164589] ./include/linux/kvm_host.h:605 suspicious rcu_dereference_check() usage! [12704.164602] other info that might help us debug this: [12704.164616] rcu_scheduler_active = 2, debug_locks = 1 [12704.164631] 6 locks held by qemu-system-aar/13968: [12704.164644] #0: 000000007ebdae4f (&kvm->lock){+.+.}, at: vgic_its_set_attr+0x244/0x3a0 [12704.164691] #1: 000000007d751022 (&its->its_lock){+.+.}, at: vgic_its_set_attr+0x250/0x3a0 [12704.164726] #2: 00000000219d2706 (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [12704.164761] #3: 00000000a760aecd (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [12704.164794] #4: 000000000ef8e31d (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [12704.164827] #5: 000000007a872093 (&vcpu->mutex){+.+.}, at: lock_all_vcpus+0x64/0xd0 [12704.164861] stack backtrace: [12704.164878] CPU: 2 PID: 13968 Comm: qemu-system-aar Tainted: G W 5.1.0-rc1-00008-g600025238f51-dirty #16 [12704.164887] Hardware name: rockchip evb_rk3399/evb_rk3399, BIOS 2019.04-rc3-00124-g2feec69fb1 03/15/2019 [12704.164896] Call trace: [12704.164910] dump_backtrace+0x0/0x138 [12704.164920] show_stack+0x24/0x30 [12704.164934] dump_stack+0xbc/0x104 [12704.164946] lockdep_rcu_suspicious+0xcc/0x110 [12704.164958] gfn_to_memslot+0x174/0x190 [12704.164969] kvm_is_visible_gfn+0x28/0x70 [12704.164980] vgic_its_check_id.isra.0+0xec/0x1e8 [12704.164991] vgic_its_save_tables_v0+0x1ac/0x330 [12704.165001] vgic_its_set_attr+0x298/0x3a0 [12704.165012] kvm_device_ioctl_attr+0x9c/0xd8 [12704.165022] kvm_device_ioctl+0x8c/0xf8 [12704.165035] do_vfs_ioctl+0xc8/0x960 [12704.165045] ksys_ioctl+0x8c/0xa0 [12704.165055] __arm64_sys_ioctl+0x28/0x38 [12704.165067] el0_svc_common+0xd8/0x138 [12704.165078] el0_svc_handler+0x38/0x78 [12704.165089] el0_svc+0x8/0xc Make sure the lock is taken when doing this. Fixes: bf308242ab98 ("KVM: arm/arm64: VGIC/ITS: protect kvm_read_guest() calls with SRCU lock") Reviewed-by: Eric Auger Signed-off-by: Marc Zyngier --- virt/kvm/arm/vgic/vgic-its.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'virt/kvm/arm/vgic/vgic-its.c') diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c index c41e11fd841c..fcb2fceaa4a5 100644 --- a/virt/kvm/arm/vgic/vgic-its.c +++ b/virt/kvm/arm/vgic/vgic-its.c @@ -754,8 +754,9 @@ static bool vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id, u64 indirect_ptr, type = GITS_BASER_TYPE(baser); phys_addr_t base = GITS_BASER_ADDR_48_to_52(baser); int esz = GITS_BASER_ENTRY_SIZE(baser); - int index; + int index, idx; gfn_t gfn; + bool ret; switch (type) { case GITS_BASER_TYPE_DEVICE: @@ -782,7 +783,8 @@ static bool vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id, if (eaddr) *eaddr = addr; - return kvm_is_visible_gfn(its->dev->kvm, gfn); + + goto out; } /* calculate and check the index into the 1st level */ @@ -812,7 +814,12 @@ static bool vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id, if (eaddr) *eaddr = indirect_ptr; - return kvm_is_visible_gfn(its->dev->kvm, gfn); + +out: + idx = srcu_read_lock(&its->dev->kvm->srcu); + ret = kvm_is_visible_gfn(its->dev->kvm, gfn); + srcu_read_unlock(&its->dev->kvm->srcu, idx); + return ret; } static int vgic_its_alloc_collection(struct vgic_its *its, -- cgit From d9ea27a3304812500de3674981a9c3a2086d517b Mon Sep 17 00:00:00 2001 From: YueHaibing Date: Wed, 20 Mar 2019 22:18:13 +0800 Subject: KVM: arm/arm64: vgic-its: Make attribute accessors static Fix sparse warnings: arch/arm64/kvm/../../../virt/kvm/arm/vgic/vgic-its.c:1732:5: warning: symbol 'vgic_its_has_attr_regs' was not declared. Should it be static? arch/arm64/kvm/../../../virt/kvm/arm/vgic/vgic-its.c:1753:5: warning: symbol 'vgic_its_attr_regs_access' was not declared. Should it be static? Signed-off-by: YueHaibing [maz: fixed subject] Signed-off-by: Marc Zyngier --- virt/kvm/arm/vgic/vgic-its.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'virt/kvm/arm/vgic/vgic-its.c') diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c index fcb2fceaa4a5..44ceaccb18cf 100644 --- a/virt/kvm/arm/vgic/vgic-its.c +++ b/virt/kvm/arm/vgic/vgic-its.c @@ -1736,8 +1736,8 @@ static void vgic_its_destroy(struct kvm_device *kvm_dev) kfree(its); } -int vgic_its_has_attr_regs(struct kvm_device *dev, - struct kvm_device_attr *attr) +static int vgic_its_has_attr_regs(struct kvm_device *dev, + struct kvm_device_attr *attr) { const struct vgic_register_region *region; gpa_t offset = attr->attr; @@ -1757,9 +1757,9 @@ int vgic_its_has_attr_regs(struct kvm_device *dev, return 0; } -int vgic_its_attr_regs_access(struct kvm_device *dev, - struct kvm_device_attr *attr, - u64 *reg, bool is_write) +static int vgic_its_attr_regs_access(struct kvm_device *dev, + struct kvm_device_attr *attr, + u64 *reg, bool is_write) { const struct vgic_register_region *region; struct vgic_its *its; -- cgit