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linux-sg2042/arch/arm64/kvm
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Dave Martin b3eb56b629 KVM: arm64/sve: Fix SVE trap restoration for non-current tasks 
Commit e6b673b ("KVM: arm64: Optimise FPSIMD handling to reduce
guest/host thrashing") attempts to restore the configuration of
userspace SVE trapping via a call to fpsimd_bind_task_to_cpu(), but
the logic for determining when to do this is not correct.

The patch makes the errnoenous assumption that the only task that
may try to enter userspace with the currently loaded FPSIMD/SVE
register content is current.  This may not be the case however:  if
some other user task T is scheduled on the CPU during the execution
of the KVM run loop, and the vcpu does not try to use the registers
in the meantime, then T's state may be left there intact.  If T
happens to be the next task to enter userspace on this CPU then the
hooks for reloading the register state and configuring traps will
be skipped.

(Also, current never has SVE state at this point anyway and should
always have the trap enabled, as a side-effect of the ioctl()
syscall needed to reach the KVM run loop in the first place.)

This patch instead restores the state of the EL0 trap from the
state observed at the most recent vcpu_load(), ensuring that the
trap is set correctly for the loaded context (if any).

Fixes: e6b673b741 ("KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
 		2018-06-21 09:14:44 +01:00
..
hyp Small update for KVM. 2018-06-12 11:34:04 -07:00
Kconfig KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing 2018-05-25 12:28:28 +01:00
Makefile KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing 2018-05-25 12:28:28 +01:00
debug.c KVM: arm64: Repurpose vcpu_arch.debug_flags for general-purpose flags 2018-05-25 12:28:13 +01:00
fpsimd.c KVM: arm64/sve: Fix SVE trap restoration for non-current tasks 2018-06-21 09:14:44 +01:00
guest.c arm/arm64: KVM: Add PSCI version selection API 2018-04-20 16:32:23 +01:00
handle_exit.c arm/arm64: KVM: Advertise SMCCC v1.1 2018-02-06 22:54:01 +00:00
hyp-init.S arm64: KVM: Move vector offsetting from hyp-init.S to kvm_get_hyp_vector 2018-03-19 13:05:37 +00:00
hyp.S arm64: hyp-stub/KVM: Kill __hyp_get_vectors 2017-04-09 07:49:34 -07:00
inject_fault.c KVM: arm64: Prepare to handle deferred save/restore of ELR_EL1 2018-03-19 10:53:17 +00:00
irq.h KVM: arm/arm64: Enable irqchip routing 2016-07-22 18:52:01 +01:00
regmap.c KVM: arm64: Prepare to handle deferred save/restore of 32-bit registers 2018-03-19 10:53:18 +00:00
reset.c arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID 2018-05-31 18:00:59 +01:00
sys_regs.c KVM: arm64: Repurpose vcpu_arch.debug_flags for general-purpose flags 2018-05-25 12:28:13 +01:00
sys_regs.h KVM: arm64: Rewrite system register accessors to read/write functions 2018-03-19 10:53:16 +00:00
sys_regs_generic_v8.c KVM: arm64: Rewrite system register accessors to read/write functions 2018-03-19 10:53:16 +00:00
trace.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
va_layout.c arm64: KVM: Allow mapping of vectors outside of the RAM region 2018-03-19 13:06:46 +00:00
vgic-sys-reg-v3.c KVM: arm/arm64: Extract GICv3 max APRn index calculation 2017-09-05 17:33:39 +02:00