Merge tag 'perf_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Borislav Petkov:

 - Prevent unintentional page sharing by checking whether a page
   reference to a PMU samples page has been acquired properly before
   that

 - Make sure the LBR_SELECT MSR is saved/restored too

 - Reset the LBR_SELECT MSR when resetting the LBR PMU to clear any
   residual data left

* tag 'perf_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Avoid put_page() when GUP fails
  perf/x86/vlbr: Add c->flags to vlbr event constraints
  perf/x86/lbr: Reset LBR_SELECT during vlbr reset

Author: torvalds

arch/x86/events/intel/core.c

@@ -3048,8 +3048,10 @@ intel_vlbr_constraints(struct perf_event *event)
 {
 	struct event_constraint *c = &vlbr_constraint;
 
-	if (unlikely(constraint_match(c, event->hw.config)))
+	if (unlikely(constraint_match(c, event->hw.config))) {
+		event->hw.flags |= c->flags;
 		return c;
+	}
 
 	return NULL;
 }

arch/x86/events/intel/lbr.c

@@ -265,6 +265,8 @@ void intel_pmu_lbr_reset(void)
 
 	cpuc->last_task_ctx = NULL;
 	cpuc->last_log_id = 0;
+	if (!static_cpu_has(X86_FEATURE_ARCH_LBR) && cpuc->lbr_select)
+		wrmsrl(MSR_LBR_SELECT, 0);
 }
 
 /*

kernel/events/core.c

@@ -7154,7 +7154,6 @@ void perf_output_sample(struct perf_output_handle *handle,
 static u64 perf_virt_to_phys(u64 virt)
 {
 	u64 phys_addr = 0;
-	struct page *p = NULL;
 
 	if (!virt)
 		return 0;
@@ -7173,14 +7172,15 @@ static u64 perf_virt_to_phys(u64 virt)
 		 * If failed, leave phys_addr as 0.
 		 */
 		if (current->mm != NULL) {
+			struct page *p;
+
 			pagefault_disable();
-			if (get_user_page_fast_only(virt, 0, &p))
+			if (get_user_page_fast_only(virt, 0, &p)) {
 				phys_addr = page_to_phys(p) + virt % PAGE_SIZE;
+				put_page(p);
+			}
 			pagefault_enable();
 		}
-
-		if (p)
-			put_page(p);
 	}
 
 	return phys_addr;