linux-toradex.git/arch/mips/kvm/mips.c, branch v4.4.39

MIPS: KVM: Fix modular KVM under QEMU

2016-07-27T16:47:30+00:00

commit 797179bc4fe06c89e47a9f36f886f68640b423f8 upstream.

Copy __kvm_mips_vcpu_run() into unmapped memory, so that we can never
get a TLB refill exception in it when KVM is built as a module.

This was observed to happen with the host MIPS kernel running under
QEMU, due to a not entirely transparent optimisation in the QEMU TLB
handling where TLB entries replaced with TLBWR are copied to a separate
part of the TLB array. Code in those pages continue to be executable,
but those mappings persist only until the next ASID switch, even if they
are marked global.

An ASID switch happens in __kvm_mips_vcpu_run() at exception level after
switching to the guest exception base. Subsequent TLB mapped kernel
instructions just prior to switching to the guest trigger a TLB refill
exception, which enters the guest exception handlers without updating
EPC. This appears as a guest triggered TLB refill on a host kernel
mapped (host KSeg2) address, which is not handled correctly as user
(guest) mode accesses to kernel (host) segments always generate address
error exceptions.

Signed-off-by: James Hogan 
Cc: Paolo Bonzini 
Cc: Radim Krčmář 
Cc: Ralf Baechle 
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

mips/kvm: fix ioctl error handling

2016-03-09T23:34:50+00:00

commit 0178fd7dcc4451fcb90bec5e91226586962478d2 upstream.

Returning directly whatever copy_to_user(...) or copy_from_user(...)
returns may not do the right thing if there's a pagefault:
copy_to_user/copy_from_user return the number of bytes not copied in
this case, but ioctls need to return -EFAULT instead.

Fix up kvm on mips to do
	return copy_to_user(...)) ?  -EFAULT : 0;
and
	return copy_from_user(...)) ?  -EFAULT : 0;

everywhere.

Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

MIPS: KVM: Uninit VCPU in vcpu_create error path

2015-11-18T11:25:36+00:00

If either of the memory allocations in kvm_arch_vcpu_create() fail, the
vcpu which has been allocated and kvm_vcpu_init'd doesn't get uninit'd
in the error handling path. Add a call to kvm_vcpu_uninit() to fix this.

Fixes: 669e846e6c4e ("KVM/MIPS32: MIPS arch specific APIs for KVM")
Signed-off-by: James Hogan 
Cc: Ralf Baechle 
Cc: Paolo Bonzini 
Cc: Gleb Natapov 
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc:  # 3.10.x-
Signed-off-by: Paolo Bonzini

KVM: add halt_attempted_poll to VCPU stats

2015-09-16T10:17:00+00:00

This new statistic can help diagnosing VCPUs that, for any reason,
trigger bad behavior of halt_poll_ns autotuning.

For example, say halt_poll_ns = 480000, and wakeups are spaced exactly
like 479us, 481us, 479us, 481us. Then KVM always fails polling and wastes
10+20+40+80+160+320+480 = 1110 microseconds out of every
479+481+479+481+479+481+479 = 3359 microseconds. The VCPU then
is consuming about 30% more CPU than it would use without
polling.  This would show as an abnormally high number of
attempted polling compared to the successful polls.

Acked-by: Christian Borntraeger 
Signed-off-by: Paolo Bonzini

KVM: add "new" argument to kvm_arch_commit_memory_region

2015-05-28T08:42:58+00:00

This lets the function access the new memory slot without going through
kvm_memslots and id_to_memslot.  It will simplify the code when more
than one address space will be supported.

Unfortunately, the "const"ness of the new argument must be casted
away in two places.  Fixing KVM to accept const struct kvm_memory_slot
pointers would require modifications in pretty much all architectures,
and is left for later.

Reviewed-by: Radim Krcmar 
Signed-off-by: Paolo Bonzini

KVM: const-ify uses of struct kvm_userspace_memory_region

2015-05-26T10:40:13+00:00

Architecture-specific helpers are not supposed to muck with
struct kvm_userspace_memory_region contents.  Add const to
enforce this.

In order to eliminate the only write in __kvm_set_memory_region,
the cleaning of deleted slots is pulled up from update_memslots
to __kvm_set_memory_region.

Reviewed-by: Takuya Yoshikawa 
Reviewed-by: Radim Krcmar 
Signed-off-by: Paolo Bonzini

KVM: use kvm_memslots whenever possible

2015-05-26T10:40:08+00:00

kvm_memslots provides lockdep checking.  Use it consistently instead of
explicit dereferencing of kvm->memslots.

Reviewed-by: Radim Krcmar 
Signed-off-by: Paolo Bonzini

KVM: mips: use id_to_memslot correctly

2015-05-19T18:52:44+00:00

The argument to KVM_GET_DIRTY_LOG is a memslot id; it may not match the
position in the memslots array, which is sorted by gfn.

Cc: stable@vger.kernel.org
Reviewed-by: James Hogan 
Signed-off-by: Paolo Bonzini

KVM: arm/mips/x86/power use __kvm_guest_{enter|exit}

2015-05-07T09:28:22+00:00

Use __kvm_guest_{enter|exit} instead of kvm_guest_{enter|exit}
where interrupts are disabled.

Signed-off-by: Christian Borntraeger 
Signed-off-by: Paolo Bonzini

MIPS: KVM: Wire up MSA capability

2015-03-27T21:25:22+00:00

Now that the code is in place for KVM to support MIPS SIMD Architecutre
(MSA) in MIPS guests, wire up the new KVM_CAP_MIPS_MSA capability.

For backwards compatibility, the capability must be explicitly enabled
in order to detect or make use of MSA from the guest.

The capability is not supported if the hardware supports MSA vector
partitioning, since the extra support cannot be tested yet and it
extends the state that the userland program would have to save.

Signed-off-by: James Hogan 
Acked-by: Paolo Bonzini 
Cc: Ralf Baechle 
Cc: Gleb Natapov 
Cc: Jonathan Corbet 
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: linux-doc@vger.kernel.org