From 72c3c0fe54a3f3ddea8f5ca468ddf9deaf2100b7 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 23 Jul 2020 00:00:09 +0200 Subject: x86/kvm: Use generic xfer to guest work function Use the generic infrastructure to check for and handle pending work before transitioning into guest mode. This now handles TIF_NOTIFY_RESUME as well which was ignored so far. Handling it is important as this covers task work and task work will be used to offload the heavy lifting of POSIX CPU timers to thread context. Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20200722220520.979724969@linutronix.de --- arch/x86/kvm/Kconfig | 1 + arch/x86/kvm/vmx/vmx.c | 11 +++++------ arch/x86/kvm/x86.c | 15 ++++++--------- 3 files changed, 12 insertions(+), 15 deletions(-) (limited to 'arch/x86/kvm') diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index b277a2db6267..fbd5bd7a945a 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -42,6 +42,7 @@ config KVM select HAVE_KVM_MSI select HAVE_KVM_CPU_RELAX_INTERCEPT select HAVE_KVM_NO_POLL + select KVM_XFER_TO_GUEST_WORK select KVM_GENERIC_DIRTYLOG_READ_PROTECT select KVM_VFIO select SRCU diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 13745f2a5ecd..9909375ee1fd 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include @@ -5373,14 +5374,12 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu) } /* - * Note, return 1 and not 0, vcpu_run() is responsible for - * morphing the pending signal into the proper return code. + * Note, return 1 and not 0, vcpu_run() will invoke + * xfer_to_guest_mode() which will create a proper return + * code. */ - if (signal_pending(current)) + if (__xfer_to_guest_mode_work_pending()) return 1; - - if (need_resched()) - schedule(); } return 1; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 88c593f83b28..82d4a9e88908 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -56,6 +56,7 @@ #include #include #include +#include #include @@ -1587,7 +1588,7 @@ EXPORT_SYMBOL_GPL(kvm_emulate_wrmsr); bool kvm_vcpu_exit_request(struct kvm_vcpu *vcpu) { return vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu) || - need_resched() || signal_pending(current); + xfer_to_guest_mode_work_pending(); } EXPORT_SYMBOL_GPL(kvm_vcpu_exit_request); @@ -8681,15 +8682,11 @@ static int vcpu_run(struct kvm_vcpu *vcpu) break; } - if (signal_pending(current)) { - r = -EINTR; - vcpu->run->exit_reason = KVM_EXIT_INTR; - ++vcpu->stat.signal_exits; - break; - } - if (need_resched()) { + if (xfer_to_guest_mode_work_pending()) { srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); - cond_resched(); + r = xfer_to_guest_mode_handle_work(vcpu); + if (r) + return r; vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); } } -- cgit v1.2.3 From f3020b8891b890b48d9e1a83241e3cce518427c1 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 30 Jul 2020 09:19:01 +0200 Subject: x86/kvm: Use __xfer_to_guest_mode_work_pending() in kvm_run_vcpu() The comments explicitely explain that the work flags check and handling in kvm_run_vcpu() is done with preemption and interrupts enabled as KVM invokes the check again right before entering guest mode with interrupts disabled which guarantees that the work flags are observed and handled before VMENTER. Nevertheless the flag pending check in kvm_run_vcpu() uses the helper variant which requires interrupts to be disabled triggering an instant lockdep splat. This was caught in testing before and then not fixed up in the patch before applying. :( Use the relaxed and intentionally racy __xfer_to_guest_mode_work_pending() instead. Fixes: 72c3c0fe54a3 ("x86/kvm: Use generic xfer to guest work function") Reported-by: Qian Cai writes: Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/87bljxa2sa.fsf@nanos.tec.linutronix.de --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kvm') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 82d4a9e88908..532597265c50 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8682,7 +8682,7 @@ static int vcpu_run(struct kvm_vcpu *vcpu) break; } - if (xfer_to_guest_mode_work_pending()) { + if (__xfer_to_guest_mode_work_pending()) { srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); r = xfer_to_guest_mode_handle_work(vcpu); if (r) -- cgit v1.2.3