In order to allow the gdbstub of QEMU to push (soft) breakpoint handling
completely into the gdb frontend, this patch enables guest exits also
for #BP exceptions - in case guest debugging was turned on.
Along this enhancement, this patch also fixes the flag manipulation for
the singlestep mode.
---
arch/x86/kvm/vmx.c | 38 +++++++++++++++-----------------------
1 file changed, 15 insertions(+), 23 deletions(-)
Index: b/arch/x86/kvm/vmx.c
===================================================================
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -461,7 +461,7 @@ static void update_exception_bitmap(stru
if (!vcpu->fpu_active)
eb |= 1u << NM_VECTOR;
if (vcpu->guest_debug.enabled)
- eb |= 1u << 1;
+ eb |= (1u << 1) | (1u << 3);
if (vcpu->arch.rmode.active)
eb = ~0;
if (vm_need_ept())
@@ -949,6 +949,7 @@ static int set_guest_debug(struct kvm_vc
{
unsigned long dr7 = 0x400;
int old_singlestep;
+ unsigned long flags;
old_singlestep = vcpu->guest_debug.singlestep;
@@ -969,13 +970,12 @@ static int set_guest_debug(struct kvm_vc
} else
vcpu->guest_debug.singlestep = 0;
- if (old_singlestep && !vcpu->guest_debug.singlestep) {
- unsigned long flags;
-
- flags = vmcs_readl(GUEST_RFLAGS);
+ flags = vmcs_readl(GUEST_RFLAGS);
+ if (vcpu->guest_debug.singlestep)
+ flags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
+ else if (old_singlestep && !vcpu->guest_debug.singlestep)
flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);
- vmcs_writel(GUEST_RFLAGS, flags);
- }
+ vmcs_writel(GUEST_RFLAGS, flags);
update_exception_bitmap(vcpu);
vmcs_writel(GUEST_DR7, dr7);
@@ -2192,14 +2192,6 @@ static void kvm_guest_debug_pre(struct k
set_debugreg(dbg->bp[1], 1);
set_debugreg(dbg->bp[2], 2);
set_debugreg(dbg->bp[3], 3);
-
- if (dbg->singlestep) {
- unsigned long flags;
-
- flags = vmcs_readl(GUEST_RFLAGS);
- flags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
- vmcs_writel(GUEST_RFLAGS, flags);
- }
}
static int handle_rmode_exception(struct kvm_vcpu *vcpu,
@@ -2221,7 +2213,7 @@ static int handle_rmode_exception(struct
static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- u32 intr_info, error_code;
+ u32 intr_info, ex_no, error_code;
unsigned long cr2, rip;
u32 vect_info;
enum emulation_result er;
@@ -2279,15 +2271,15 @@ static int handle_exception(struct kvm_v
return 1;
}
- if ((intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK)) ==
- (INTR_TYPE_EXCEPTION | 1)) {
+ ex_no = intr_info & INTR_INFO_VECTOR_MASK;
+ if (ex_no == 1 || ex_no == 3) {
kvm_run->exit_reason = KVM_EXIT_DEBUG;
- kvm_run->debug.arch.exception = 1;
- return 0;
+ kvm_run->debug.arch.exception = ex_no;
+ } else {
+ kvm_run->exit_reason = KVM_EXIT_EXCEPTION;
+ kvm_run->ex.exception = ex_no;
+ kvm_run->ex.error_code = error_code;
}
- kvm_run->exit_reason = KVM_EXIT_EXCEPTION;
- kvm_run->ex.exception = intr_info & INTR_INFO_VECTOR_MASK;
- kvm_run->ex.error_code = error_code;
return 0;
}
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