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diff --git a/sys/amd64/include/vmm.h b/sys/amd64/include/vmm.h
--- a/sys/amd64/include/vmm.h
+++ b/sys/amd64/include/vmm.h
@@ -497,6 +497,7 @@
VM_CAP_RDTSCP,
VM_CAP_IPI_EXIT,
VM_CAP_MASK_HWINTR,
+ VM_CAP_RFLAGS_TF,
VM_CAP_MAX
};
@@ -645,6 +646,7 @@
VM_EXITCODE_VMINSN,
VM_EXITCODE_BPT,
VM_EXITCODE_IPI,
+ VM_EXITCODE_DB,
VM_EXITCODE_MAX
};
@@ -734,6 +736,12 @@
struct {
int inst_length;
} bpt;
+ struct {
+ int trace_trap;
+ int pushf_intercept;
+ int tf_shadow_val;
+ struct vm_guest_paging paging;
+ } dbg;
struct {
uint32_t code; /* ecx value */
uint64_t wval;
diff --git a/sys/amd64/vmm/amd/svm.c b/sys/amd64/vmm/amd/svm.c
--- a/sys/amd64/vmm/amd/svm.c
+++ b/sys/amd64/vmm/amd/svm.c
@@ -131,7 +131,7 @@
static int svm_getdesc(void *vcpui, int reg, struct seg_desc *desc);
static int svm_setreg(void *vcpui, int ident, uint64_t val);
-
+static int svm_getreg(void *vcpui, int ident, uint64_t *val);
static __inline int
flush_by_asid(void)
{
@@ -1282,6 +1282,8 @@
{ .reason = VMCB_EXIT_ICEBP, .str = "icebp" },
{ .reason = VMCB_EXIT_INVD, .str = "invd" },
{ .reason = VMCB_EXIT_INVLPGA, .str = "invlpga" },
+ { .reason = VMCB_EXIT_POPF, .str = "popf" },
+ { .reason = VMCB_EXIT_PUSHF, .str = "pushf" },
};
for (i = 0; i < nitems(reasons); i++) {
@@ -1419,7 +1421,63 @@
errcode_valid = 1;
info1 = 0;
break;
-
+ case IDT_DB: {
+ /*
+ * Check if we are being stepped (RFLAGS.TF)
+ * and bounce vmexit to userland.
+ */
+ bool stepped = 0;
+ uint64_t dr6 = 0;
+
+ svm_getreg(vcpu, VM_REG_GUEST_DR6, &dr6);
+ stepped = !!(dr6 & DBREG_DR6_BS);
+ if (stepped && (vcpu->caps & (1 << VM_CAP_RFLAGS_TF))) {
+ vmexit->exitcode = VM_EXITCODE_DB;
+ vmexit->u.dbg.trace_trap = 1;
+ vmexit->u.dbg.pushf_intercept = 0;
+
+ if (vcpu->dbg.popf_sstep) {
+ /* DB exit was caused by stepping over
+ * popf */
+ uint64_t rflags;
+
+ vcpu->dbg.popf_sstep = 0;
+ /*
+ * Update shadowed TF bit so the next
+ * setcap(..., RFLAGS_SSTEP, 0) restores
+ * the correct value
+ */
+ svm_getreg(vcpu, VM_REG_GUEST_RFLAGS,
+ &rflags);
+ vcpu->dbg.rflags_tf = rflags & PSL_T;
+ } else if (vcpu->dbg.pushf_sstep) {
+ /* DB exit was caused by stepping over
+ * pushf */
+ vcpu->dbg.pushf_sstep = 0;
+ /*
+ * Adjusting the pushed rflags after a
+ * restarted pushf instruction must be
+ * handled outside of svm.c due to the
+ * critical_enter() lock being held.
+ */
+ vmexit->u.dbg.pushf_intercept = 1;
+ vmexit->u.dbg.tf_shadow_val =
+ vcpu->dbg.rflags_tf;
+ svm_paging_info(svm_get_vmcb(vcpu),
+ &vmexit->u.dbg.paging);
+ }
+ /* Clear DR6 "single-step" bit. */
+ dr6 &= ~DBREG_DR6_BS;
+ error = svm_setreg(vcpu, VM_REG_GUEST_DR6, dr6);
+ KASSERT(error == 0,
+ ("%s: error %d updating DR6\r\n", __func__,
+ error));
+
+ reflect = 0;
+ handled = 0;
+ }
+ break;
+ }
case IDT_BP:
vmexit->exitcode = VM_EXITCODE_BPT;
vmexit->u.bpt.inst_length = vmexit->inst_length;
@@ -1546,6 +1604,42 @@
case VMCB_EXIT_MWAIT:
vmexit->exitcode = VM_EXITCODE_MWAIT;
break;
+ case VMCB_EXIT_PUSHF: {
+ if (vcpu->caps & (1 << VM_CAP_RFLAGS_TF)) {
+ uint64_t rflags;
+
+ svm_getreg(vcpu, VM_REG_GUEST_RFLAGS, &rflags);
+ /* Restart this instruction. */
+ vmexit->inst_length = 0;
+ /* Disable PUSHF intercepts - avoid a loop. */
+ svm_set_intercept(vcpu, VMCB_CTRL1_INTCPT,
+ VMCB_INTCPT_PUSHF, 0);
+ /* Trace restarted instruction. */
+ svm_setreg(vcpu, VM_REG_GUEST_RFLAGS, (rflags | PSL_T));
+ /* Let the IDT_DB handler know that pushf was stepped.
+ */
+ vcpu->dbg.pushf_sstep = 1;
+ handled = 1;
+ }
+ break;
+ }
+ case VMCB_EXIT_POPF: {
+ if (vcpu->caps & (1 << VM_CAP_RFLAGS_TF)) {
+ uint64_t rflags;
+
+ svm_getreg(vcpu, VM_REG_GUEST_RFLAGS, &rflags);
+ /* Restart this instruction */
+ vmexit->inst_length = 0;
+ /* Disable POPF intercepts - avoid a loop*/
+ svm_set_intercept(vcpu, VMCB_CTRL1_INTCPT,
+ VMCB_INTCPT_POPF, 0);
+ /* Trace restarted instruction */
+ svm_setreg(vcpu, VM_REG_GUEST_RFLAGS, (rflags | PSL_T));
+ vcpu->dbg.popf_sstep = 1;
+ handled = 1;
+ }
+ break;
+ }
case VMCB_EXIT_SHUTDOWN:
case VMCB_EXIT_VMRUN:
case VMCB_EXIT_VMMCALL:
@@ -2347,6 +2441,50 @@
vlapic = vm_lapic(vcpu->vcpu);
vlapic->ipi_exit = val;
break;
+ case VM_CAP_RFLAGS_TF: {
+ uint64_t rflags;
+
+ /* Fetch RFLAGS. */
+ if (svm_getreg(vcpu, VM_REG_GUEST_RFLAGS, &rflags)) {
+ error = (EINVAL);
+ break;
+ }
+ if (val) {
+ /* Save current TF bit. */
+ vcpu->dbg.rflags_tf = rflags & PSL_T;
+ /* Trace next instruction. */
+ if (svm_setreg(vcpu, VM_REG_GUEST_RFLAGS,
+ (rflags | PSL_T))) {
+ error = (EINVAL);
+ break;
+ }
+ vcpu->caps |= (1 << VM_CAP_RFLAGS_TF);
+ } else {
+ /*
+ * Restore shadowed RFLAGS.TF only if vCPU was
+ * previously stepped
+ */
+ if (vcpu->caps & (1 << VM_CAP_RFLAGS_TF)) {
+ rflags &= ~PSL_T;
+ rflags |= vcpu->dbg.rflags_tf;
+ vcpu->dbg.rflags_tf = 0;
+
+ if (svm_setreg(vcpu, VM_REG_GUEST_RFLAGS,
+ rflags)) {
+ error = (EINVAL);
+ break;
+ }
+ vcpu->caps &= ~(1 << VM_CAP_RFLAGS_TF);
+ }
+ }
+
+ svm_set_intercept(vcpu, VMCB_EXC_INTCPT, BIT(IDT_DB), val);
+ svm_set_intercept(vcpu, VMCB_CTRL1_INTCPT, VMCB_INTCPT_POPF,
+ val);
+ svm_set_intercept(vcpu, VMCB_CTRL1_INTCPT, VMCB_INTCPT_PUSHF,
+ val);
+ break;
+ }
default:
error = ENOENT;
break;
@@ -2383,6 +2521,9 @@
vlapic = vm_lapic(vcpu->vcpu);
*retval = vlapic->ipi_exit;
break;
+ case VM_CAP_RFLAGS_TF:
+ *retval = !!(vcpu->caps & (1 << VM_CAP_RFLAGS_TF));
+ break;
default:
error = ENOENT;
break;
diff --git a/sys/amd64/vmm/amd/svm_softc.h b/sys/amd64/vmm/amd/svm_softc.h
--- a/sys/amd64/vmm/amd/svm_softc.h
+++ b/sys/amd64/vmm/amd/svm_softc.h
@@ -36,6 +36,12 @@
struct svm_softc;
+struct dbg {
+ uint32_t rflags_tf; /* saved RFLAGS.TF value when single-stepping a vcpu */
+ bool popf_sstep; /* indicates that we've stepped over popf */
+ bool pushf_sstep; /* indicates that we've stepped over pushf */
+};
+
struct asid {
uint64_t gen; /* range is [1, ~0UL] */
uint32_t num; /* range is [1, nasid - 1] */
@@ -54,6 +60,8 @@
struct asid asid;
struct vm_mtrr mtrr;
int vcpuid;
+ struct dbg dbg;
+ int caps; /* optional vm capabilities */
};
/*
diff --git a/sys/amd64/vmm/vmm.c b/sys/amd64/vmm/vmm.c
--- a/sys/amd64/vmm/vmm.c
+++ b/sys/amd64/vmm/vmm.c
@@ -1746,6 +1746,39 @@
return (0);
}
+static int
+vm_handle_db(struct vcpu *vcpu, struct vm_exit *vme, bool *retu)
+{
+ int error, fault;
+ uint64_t rsp;
+ uint64_t rflags;
+ struct vm_copyinfo copyinfo;
+
+ *retu = true;
+ if (!vme->u.dbg.pushf_intercept) {
+ return (0);
+ }
+
+ vm_get_register(vcpu, VM_REG_GUEST_RSP, &rsp);
+ error = vm_copy_setup(vcpu, &vme->u.dbg.paging, rsp, sizeof(uint64_t),
+ VM_PROT_RDWR, &copyinfo, 1, &fault);
+ if (error || fault) {
+ *retu = false;
+ return (EINVAL);
+ }
+
+ /* Read pushed rflags value from top of stack. */
+ vm_copyin(&copyinfo, &rflags, sizeof(uint64_t));
+ /* Set TF bit to shadowed value. */
+ rflags &= ~(PSL_T);
+ rflags |= vme->u.dbg.tf_shadow_val;
+ /* Write updated value back to memory. */
+ vm_copyout(&rflags, &copyinfo, sizeof(uint64_t));
+ vm_copy_teardown(&copyinfo, 1);
+
+ return (0);
+}
+
int
vm_suspend(struct vm *vm, enum vm_suspend_how how)
{
@@ -1914,6 +1947,9 @@
case VM_EXITCODE_INOUT_STR:
error = vm_handle_inout(vcpu, vme, &retu);
break;
+ case VM_EXITCODE_DB:
+ error = vm_handle_db(vcpu, vme, &retu);
+ break;
case VM_EXITCODE_MONITOR:
case VM_EXITCODE_MWAIT:
case VM_EXITCODE_VMINSN:

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