From c6986f16a7022ccfb73d91bc7676c8e1d15e5342 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 1 Mar 2021 12:02:44 +0100 Subject: [PATCH] KVM: x86: do not fail if software breakpoint has already been removed If kvm_arch_remove_sw_breakpoint finds that a software breakpoint does not have an INT3 instruction, it fails. This can happen if one sets a software breakpoint in a kernel module and then reloads it. gdb then thinks the breakpoint cannot be deleted and there is no way to add it back. Suggested-by: Maxim Levitsky Reviewed-by: Maxim Levitsky Signed-off-by: Paolo Bonzini --- target/i386/kvm/kvm.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 0b5755e42b..c8d61daf68 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -4352,8 +4352,13 @@ int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp) { uint8_t int3; - if (cpu_memory_rw_debug(cs, bp->pc, &int3, 1, 0) || int3 != 0xcc || - cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 1, 1)) { + if (cpu_memory_rw_debug(cs, bp->pc, &int3, 1, 0)) { + return -EINVAL; + } + if (int3 != 0xcc) { + return 0; + } + if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 1, 1)) { return -EINVAL; } return 0;