linux-stable.git/virt/kvm/arm, branch linux-5.0.y

KVM: arm/arm64: Ensure vcpu target is unset on reset failure

2019-05-25T16:22:27+00:00

[ Upstream commit 811328fc3222f7b55846de0cd0404339e2e1e6d7 ]

A failed KVM_ARM_VCPU_INIT should not set the vcpu target,
as the vcpu target is used by kvm_vcpu_initialized() to
determine if other vcpu ioctls may proceed. We need to set
the target before calling kvm_reset_vcpu(), but if that call
fails, we should then unset it and clear the feature bitmap
while we're at it.

Signed-off-by: Andrew Jones 
[maz: Simplified patch, completed commit message]
Signed-off-by: Marc Zyngier 
Signed-off-by: Sasha Levin

KVM: arm/arm64: Fix handling of stage2 huge mappings

2019-05-04T07:21:15+00:00

[ Upstream commit 3c3736cd32bf5197aed1410ae826d2d254a5b277 ]

We rely on the mmu_notifier call backs to handle the split/merge
of huge pages and thus we are guaranteed that, while creating a
block mapping, either the entire block is unmapped at stage2 or it
is missing permission.

However, we miss a case where the block mapping is split for dirty
logging case and then could later be made block mapping, if we cancel the
dirty logging. This not only creates inconsistent TLB entries for
the pages in the the block, but also leakes the table pages for
PMD level.

Handle this corner case for the huge mappings at stage2 by
unmapping the non-huge mapping for the block. This could potentially
release the upper level table. So we need to restart the table walk
once we unmap the range.

Fixes : ad361f093c1e31d ("KVM: ARM: Support hugetlbfs backed huge pages")
Reported-by: Zheng Xiang 
Cc: Zheng Xiang 
Cc: Zenghui Yu 
Cc: Christoffer Dall 
Signed-off-by: Suzuki K Poulose 
Signed-off-by: Marc Zyngier 
Signed-off-by: Sasha Levin (Microsoft)

KVM: arm/arm64: vgic-its: Take the srcu lock when parsing the memslots

2019-05-04T07:21:15+00:00

[ Upstream commit 7494cec6cb3ba7385a6a223b81906384f15aae34 ]

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 
Signed-off-by: Sasha Levin (Microsoft)

KVM: arm/arm64: vgic-its: Take the srcu lock when writing to guest memory

2019-05-04T07:21:15+00:00

[ Upstream commit a6ecfb11bf37743c1ac49b266595582b107b61d4 ]

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 
Signed-off-by: Sasha Levin (Microsoft)

arm64: KVM: Always set ICH_HCR_EL2.EN if GICv4 is enabled

2019-05-04T07:21:15+00:00

[ Upstream commit ca71228b42a96908eca7658861eafacd227856c9 ]

The normal interrupt flow is not to enable the vgic when no virtual
interrupt is to be injected (i.e. the LRs are empty). But when a guest
is likely to use GICv4 for LPIs, we absolutely need to switch it on
at all times. Otherwise, VLPIs only get delivered when there is something
in the LRs, which doesn't happen very often.

Reported-by: Nianyao Tang 
Tested-by: Shameerali Kolothum Thodi 
Signed-off-by: Marc Zyngier 
Signed-off-by: Sasha Levin (Microsoft)

KVM: Call kvm_arch_memslots_updated() before updating memslots

2019-03-23T19:11:40+00:00

commit 152482580a1b0accb60676063a1ac57b2d12daf6 upstream.

kvm_arch_memslots_updated() is at this point in time an x86-specific
hook for handling MMIO generation wraparound.  x86 stashes 19 bits of
the memslots generation number in its MMIO sptes in order to avoid
full page fault walks for repeat faults on emulated MMIO addresses.
Because only 19 bits are used, wrapping the MMIO generation number is
possible, if unlikely.  kvm_arch_memslots_updated() alerts x86 that
the generation has changed so that it can invalidate all MMIO sptes in
case the effective MMIO generation has wrapped so as to avoid using a
stale spte, e.g. a (very) old spte that was created with generation==0.

Given that the purpose of kvm_arch_memslots_updated() is to prevent
consuming stale entries, it needs to be called before the new generation
is propagated to memslots.  Invalidating the MMIO sptes after updating
memslots means that there is a window where a vCPU could dereference
the new memslots generation, e.g. 0, and incorrectly reuse an old MMIO
spte that was created with (pre-wrap) generation==0.

Fixes: e59dbe09f8e6 ("KVM: Introduce kvm_arch_memslots_updated()")
Cc: 
Signed-off-by: Sean Christopherson 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

KVM: arm64: Relax the restriction on using stage2 PUD huge mapping

2019-02-07T11:44:47+00:00

We restrict mapping the PUD huge pages in stage2 to only when the
stage2 has 4 level page table, leaving the feature unused with
the default IPA size. But we could use it even with a 3
level page table, i.e, when the PUD level is folded into PGD,
just like the stage1. Relax the condition to allow using the
PUD huge page mappings at stage2 when it is possible.

Cc: Christoffer Dall 
Reviewed-by: Marc Zyngier 
Signed-off-by: Suzuki K Poulose 
Signed-off-by: Marc Zyngier

KVM: arm/arm64: vgic: Always initialize the group of private IRQs

2019-02-07T11:44:47+00:00

We currently initialize the group of private IRQs during
kvm_vgic_vcpu_init, and the value of the group depends on the GIC model
we are emulating.  However, CPUs created before creating (and
initializing) the VGIC might end up with the wrong group if the VGIC
is created as GICv3 later.

Since we have no enforced ordering of creating the VGIC and creating
VCPUs, we can end up with part the VCPUs being properly intialized and
the remaining incorrectly initialized.  That also means that we have no
single place to do the per-cpu data structure initialization which
depends on knowing the emulated GIC model (which is only the group
field).

This patch removes the incorrect comment from kvm_vgic_vcpu_init and
initializes the group of all previously created VCPUs's private
interrupts in vgic_init in addition to the existing initialization in
kvm_vgic_vcpu_init.

Signed-off-by: Christoffer Dall 
Signed-off-by: Marc Zyngier

arm/arm64: KVM: Allow a VCPU to fully reset itself

2019-02-07T11:44:13+00:00

The current kvm_psci_vcpu_on implementation will directly try to
manipulate the state of the VCPU to reset it.  However, since this is
not done on the thread that runs the VCPU, we can end up in a strangely
corrupted state when the source and target VCPUs are running at the same
time.

Fix this by factoring out all reset logic from the PSCI implementation
and forwarding the required information along with a request to the
target VCPU.

Reviewed-by: Andrew Jones 
Signed-off-by: Marc Zyngier 
Signed-off-by: Christoffer Dall

KVM: arm/arm64: vgic: Make vgic_cpu->ap_list_lock a raw_spinlock

2019-01-24T14:09:09+00:00

vgic_cpu->ap_list_lock must always be taken with interrupts disabled as
it is used in interrupt context.

For configurations such as PREEMPT_RT_FULL, this means that it should
be a raw_spinlock since RT spinlocks are interruptible.

Signed-off-by: Julien Thierry 
Acked-by: Christoffer Dall 
Acked-by: Marc Zyngier 
Signed-off-by: Christoffer Dall