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
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boot	ARM: SoC: late updates	2018-06-11 18:19:45 -07:00
configs	ARM: SoC platform updates	2018-06-11 17:49:09 -07:00
crypto	crypto: clarify licensing of OpenSSL asm code	2018-05-31 00:13:44 +08:00
include	KVM: arm64/sve: Fix SVE trap restoration for non-current tasks	2018-06-21 09:14:44 +01:00
kernel	Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables	2018-06-14 12:21:18 +09:00
kvm	KVM: arm64/sve: Fix SVE trap restoration for non-current tasks	2018-06-21 09:14:44 +01:00
lib
mm	treewide: use PHYS_ADDR_MAX to avoid type casting ULLONG_MAX	2018-06-15 07:55:25 +09:00
net
xen
Kconfig	Kbuild: rename HAVE_CC_STACKPROTECTOR config variable	2018-06-15 07:15:28 +09:00
Kconfig.debug
Kconfig.platforms
Makefile	arm64: move GCC version check for ARCH_SUPPORTS_INT128 to Kconfig	2018-06-08 18:56:02 +09:00