From: Alexander Popov Date: Mon, 21 Jan 2019 12:48:40 +0000 (+0300) Subject: KVM: x86: Fix single-step debugging X-Git-Tag: v5.15~7094^2~16 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5cc244a20b86090c087073c124284381cdf47234;p=platform%2Fkernel%2Flinux-starfive.git KVM: x86: Fix single-step debugging The single-step debugging of KVM guests on x86 is broken: if we run gdb 'stepi' command at the breakpoint when the guest interrupts are enabled, RIP always jumps to native_apic_mem_write(). Then other nasty effects follow. Long investigation showed that on Jun 7, 2017 the commit c8401dda2f0a00cd25c0 ("KVM: x86: fix singlestepping over syscall") introduced the kvm_run.debug corruption: kvm_vcpu_do_singlestep() can be called without X86_EFLAGS_TF set. Let's fix it. Please consider that for -stable. Signed-off-by: Alexander Popov Cc: stable@vger.kernel.org Fixes: c8401dda2f0a00cd25c0 ("KVM: x86: fix singlestepping over syscall") Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 02c8e09..f14bb80 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6480,8 +6480,7 @@ restart: toggle_interruptibility(vcpu, ctxt->interruptibility); vcpu->arch.emulate_regs_need_sync_to_vcpu = false; kvm_rip_write(vcpu, ctxt->eip); - if (r == EMULATE_DONE && - (ctxt->tf || (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP))) + if (r == EMULATE_DONE && ctxt->tf) kvm_vcpu_do_singlestep(vcpu, &r); if (!ctxt->have_exception || exception_type(ctxt->exception.vector) == EXCPT_TRAP)