From 6758034e4d6a7f0e26b748789ab1f83f3116d1b9 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 28 May 2020 16:13:52 -0400 Subject: x86/process/64: Make save_fsgs_for_kvm() ready for FSGSBASE save_fsgs_for_kvm() is invoked via vcpu_enter_guest() kvm_x86_ops.prepare_guest_switch(vcpu) vmx_prepare_switch_to_guest() save_fsgs_for_kvm() with preemption disabled, but interrupts enabled. The upcoming FSGSBASE based GS safe needs interrupts to be disabled. This could be done in the helper function, but that function is also called from switch_to() which has interrupts disabled already. Disable interrupts inside save_fsgs_for_kvm() and rename the function to current_save_fsgs() so it can be invoked from other places. Signed-off-by: Thomas Gleixner Signed-off-by: Sasha Levin Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20200528201402.1708239-7-sashal@kernel.org --- arch/x86/kernel/process_64.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) (limited to 'arch/x86/kernel/process_64.c') diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index c41e0aae8426..ef2f75588f41 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -240,18 +240,21 @@ static __always_inline void save_fsgs(struct task_struct *task) save_base_legacy(task, task->thread.gsindex, GS); } -#if IS_ENABLED(CONFIG_KVM) /* * While a process is running,current->thread.fsbase and current->thread.gsbase - * may not match the corresponding CPU registers (see save_base_legacy()). KVM - * wants an efficient way to save and restore FSBASE and GSBASE. - * When FSGSBASE extensions are enabled, this will have to use RD{FS,GS}BASE. + * may not match the corresponding CPU registers (see save_base_legacy()). */ -void save_fsgs_for_kvm(void) +void current_save_fsgs(void) { + unsigned long flags; + + /* Interrupts need to be off for FSGSBASE */ + local_irq_save(flags); save_fsgs(current); + local_irq_restore(flags); } -EXPORT_SYMBOL_GPL(save_fsgs_for_kvm); +#if IS_ENABLED(CONFIG_KVM) +EXPORT_SYMBOL_GPL(current_save_fsgs); #endif static __always_inline void loadseg(enum which_selector which, -- cgit