commit dc737cafcbc0d030d797b66a45ccf9fe92d09700
parent c017dafb1efb1e28b9f5b3500bf5f87e451709d5
Author: Louis Burda <quent.burda@gmail.com>
Date: Mon, 6 Feb 2023 11:23:10 -0600
Use retired instructions in userspace for TRACK_STEPS
Diffstat:
2 files changed, 47 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
@@ -3978,9 +3978,10 @@ static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu,
cpc_untrack_single(vcpu, fault->gfn, modes[i]);
- if (cpc_track_steps.use_target && !cpc_track_steps.stepping
+ if (cpc_track_steps.use_target && !cpc_track_steps.in_target
&& inst_fetch && fault->gfn == cpc_track_steps.target_gfn) {
CPC_INFO("Entering target gfn for stepping\n");
+ cpc_track_steps.in_target = true;
cpc_track_steps.stepping = true;
cpc_untrack_single(vcpu, fault->gfn,
KVM_PAGE_TRACK_EXEC);
@@ -3993,9 +3994,10 @@ static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu,
cpc_untrack_single(vcpu, fault->gfn,
KVM_PAGE_TRACK_EXEC);
}
- } else if (cpc_track_steps.use_target && cpc_track_steps.stepping
+ } else if (cpc_track_steps.use_target && cpc_track_steps.in_target
&& inst_fetch && fault->gfn != cpc_track_steps.target_gfn) {
CPC_INFO("Leaving target gfn for stepping\n");
+ cpc_track_steps.in_target = false;
cpc_track_steps.stepping = false;
if (cpc_track_steps.with_data) {
cpc_untrack_all(vcpu, KVM_PAGE_TRACK_ACCESS);
@@ -4023,6 +4025,9 @@ static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu,
break;
case CPC_TRACK_PAGES:
BUG_ON(modes[i] != KVM_PAGE_TRACK_EXEC);
+ /* future readers: ik this part is messy, but handling
+ * instructions on page boundaries has many cases
+ * when optimizing for the common case (not on boundary) */
if (!inst_fetch || !fault->present)
return false;
@@ -4046,8 +4051,10 @@ static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu,
cpc_track_single(vcpu, cpc_track_pages.cur_gfn,
KVM_PAGE_TRACK_EXEC);
cpc_track_pages.prev_gfn = cpc_track_pages.cur_gfn;
+ cpc_track_pages.prev_err = cpc_track_pages.cur_err;
cpc_track_pages.prev_avail = true;
cpc_track_pages.cur_gfn = cpc_track_pages.next_gfn;
+ cpc_track_pages.cur_err = cpc_track_pages.next_err;
cpc_track_pages.cur_avail = true;
cpc_track_pages.next_avail = false;
cpc_track_pages.in_step = false;
@@ -4056,41 +4063,53 @@ static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu,
cpc_untrack_single(vcpu, fault->gfn, modes[i]);
if (!cpc_track_pages.in_step) {
+ /* assume instruction is not on page boundary,
+ * retrack previous, keep current untracked.. */
if (cpc_track_pages.cur_avail) {
cpc_track_single(vcpu,
cpc_track_pages.cur_gfn, modes[i]);
cpc_send_track_page_event(cpc_track_pages.cur_gfn,
- fault->gfn, cpc_track_pages.retinst);
+ fault->gfn, fault->error_code,
+ cpc_track_pages.retinst,
+ cpc_track_pages.retinst_user);
cpc_track_pages.prev_gfn = cpc_track_pages.cur_gfn;
+ cpc_track_pages.prev_err = cpc_track_pages.cur_err;
cpc_track_pages.prev_avail = true;
}
cpc_track_pages.cur_gfn = fault->gfn;
+ cpc_track_pages.cur_err = fault->error_code;
cpc_track_pages.cur_avail = true;
cpc_track_pages.next_avail = false;
cpc_track_pages.retinst = 0;
+ cpc_track_pages.retinst_user = 0;
cpc_track_pages.in_step = true;
} else {
WARN_ON(cpc_track_pages.next_avail);
if (is_prev_gfn) {
/* instruction on boundary A -> B, but we
* untracked A previously so now its being
- * retracked load the insrtuction.
+ * retracked to load the instruction.
* reorder gfns chronologically */
cpc_track_pages.next_gfn = cpc_track_pages.cur_gfn;
+ cpc_track_pages.next_err = cpc_track_pages.cur_err;
cpc_track_pages.next_avail = true;
cpc_track_pages.cur_gfn = cpc_track_pages.prev_gfn;
+ cpc_track_pages.cur_err = cpc_track_pages.prev_err;
cpc_track_pages.cur_avail = true;
cpc_track_pages.prev_avail = false;
} else {
- /* instruction on boundary A -> B and both
- * pages need to be loaded simultaneously */
+ /* instruction on boundary B -> C in order */
cpc_track_pages.next_gfn = fault->gfn;
+ cpc_track_pages.next_err = fault->error_code;
cpc_track_pages.next_avail = true;
cpc_send_track_page_event(cpc_track_pages.cur_gfn,
cpc_track_pages.next_gfn,
- cpc_track_pages.retinst);
+ cpc_track_pages.cur_err,
+ cpc_track_pages.retinst,
+ cpc_track_pages.retinst_user);
cpc_track_pages.retinst = 0;
+ cpc_track_pages.retinst_user = 0;
}
CPC_INFO("Instruction on boundary %08llx -> %08llx\n",
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
@@ -2163,12 +2163,22 @@ static int intr_interception(struct kvm_vcpu *vcpu)
inst_gfn_seen = true;
}
if (!inst_gfn_seen && cpc_track_steps.use_filter) {
+ /* remove without retracking */
list_del(&fault->list);
kfree(fault);
}
}
- if (cpc_track_steps.stepping)
- cpc_send_track_step_event(&cpc_faults);
+
+ if (cpc_track_steps.target_user && !cpc_retinst_user) {
+ /* stop single-stepping until we leave this page */
+ CPC_INFO("Target page not userspace, skipping..\n");
+ cpc_singlestep = false;
+ cpc_prime_probe = false;
+ cpc_track_steps.stepping = false;
+ break;
+ }
+
+ cpc_send_track_step_event(&cpc_faults);
list_for_each_entry_safe(fault, next, &cpc_faults, list) {
if (cpc_track_steps.with_data && cpc_track_steps.stepping)
cpc_track_single(vcpu, fault->gfn, KVM_PAGE_TRACK_ACCESS);
@@ -3383,7 +3393,7 @@ int svm_invoke_exit_handler(struct kvm_vcpu *vcpu, u64 exit_code)
if (!svm_check_exit_valid(exit_code))
return svm_handle_invalid_exit(vcpu, exit_code);
- if (cpc_loglevel >= CPC_LOGLVL_INFO && exit_code != SVM_EXIT_INTR) {
+ if (cpc_loglevel >= CPC_LOGLVL_DBG && exit_code != SVM_EXIT_INTR) {
for (i = 0; i < sizeof(codelut) / sizeof(codelut[0]); i++) {
if (codelut[i].code == exit_code)
CPC_INFO("KVM EXIT %s (%u,%llu)\n",
@@ -3963,6 +3973,7 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
cpc_apic_timer = cpc_apic_timer_min;
cpc_retinst = cpc_read_pmc(CPC_RETINST_PMC);
+ cpc_retinst_user = cpc_read_pmc(CPC_RETINST_USER_PMC);
if (sev_es_guest(vcpu->kvm)) {
__svm_sev_es_vcpu_run(vmcb_pa);
@@ -3983,12 +3994,17 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
}
cpc_retinst = cpc_read_pmc(CPC_RETINST_PMC) - cpc_retinst;
+ cpc_retinst_user = cpc_read_pmc(CPC_RETINST_USER_PMC) - cpc_retinst_user;
if (cpc_prime_probe)
cpc_save_msrmts(cpc_ds);
- if (cpc_track_mode == CPC_TRACK_PAGES && cpc_retinst >= 1)
- cpc_track_pages.retinst += cpc_retinst - 1;
+ if (cpc_track_mode == CPC_TRACK_PAGES) {
+ if (cpc_retinst >= 1)
+ cpc_track_pages.retinst += cpc_retinst - 1;
+ if (cpc_retinst_user >= 1)
+ cpc_track_pages.retinst_user += cpc_retinst_user - 1;
+ }
put_cpu();
