KVM: arm64: Use generic KVM xfer to guest work function

mainline inclusion
from mainline-v5.14
commit 6caa5812
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4VZJT
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6caa5812e2d126a0aa8a17816c1ba6f0a0c2b309

--------------------------------

Clean up handling of checks for pending work by switching to the generic
infrastructure to do so.

We pick up handling for TIF_NOTIFY_RESUME from this switch, meaning that
task work will be correctly handled.
Signed-off-by: NOliver Upton <oupton@google.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210802192809.1851010-4-oupton@google.comSigned-off-by: NZhang Qiao <zhangqiao22@huawei.com>
Reviewed-by: NKeqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/kvm/Kconfig

@@ -28,6 +28,7 @@ menuconfig KVM
 	select HAVE_KVM_ARCH_TLB_FLUSH_ALL
 	select KVM_MMIO
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
+	select KVM_XFER_TO_GUEST_WORK
 	select SRCU
 	select KVM_VFIO
 	select HAVE_KVM_EVENTFD

arch/arm64/kvm/arm.c

@@ -6,6 +6,7 @@
 
 #include <linux/bug.h>
 #include <linux/cpu_pm.h>
+#include <linux/entry-kvm.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/kvm_host.h>
@@ -727,6 +728,45 @@ static void update_vcpu_stat_time(struct kvm_vcpu_stat *vcpu_stat)
 	vcpu_stat->gtime = current->gtime;
 }
 
+/**
+ * kvm_vcpu_exit_request - returns true if the VCPU should *not* enter the guest
+ * @vcpu:	The VCPU pointer
+ * @ret:	Pointer to write optional return code
+ *
+ * Returns: true if the VCPU needs to return to a preemptible + interruptible
+ *	    and skip guest entry.
+ *
+ * This function disambiguates between two different types of exits: exits to a
+ * preemptible + interruptible kernel context and exits to userspace. For an
+ * exit to userspace, this function will write the return code to ret and return
+ * true. For an exit to preemptible + interruptible kernel context (i.e. check
+ * for pending work and re-enter), return true without writing to ret.
+ */
+static bool kvm_vcpu_exit_request(struct kvm_vcpu *vcpu, int *ret)
+{
+	struct kvm_run *run = vcpu->run;
+
+	/*
+	 * If we're using a userspace irqchip, then check if we need
+	 * to tell a userspace irqchip about timer or PMU level
+	 * changes and if so, exit to userspace (the actual level
+	 * state gets updated in kvm_timer_update_run and
+	 * kvm_pmu_update_run below).
+	 */
+	if (static_branch_unlikely(&userspace_irqchip_in_use)) {
+		if (kvm_timer_should_notify_user(vcpu) ||
+		    kvm_pmu_should_notify_user(vcpu)) {
+			*ret = -EINTR;
+			run->exit_reason = KVM_EXIT_INTR;
+			return true;
+		}
+	}
+
+	return kvm_request_pending(vcpu) ||
+			need_new_vmid_gen(&vcpu->arch.hw_mmu->vmid) ||
+			xfer_to_guest_mode_work_pending();
+}
+
 /**
  * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
  * @vcpu:	The VCPU pointer
@@ -768,7 +808,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		/*
 		 * Check conditions before entering the guest
 		 */
-		cond_resched();
+		ret = xfer_to_guest_mode_handle_work(vcpu);
+		if (!ret)
+			ret = 1;
 
 		update_vmid(&vcpu->arch.hw_mmu->vmid);
 
@@ -787,31 +829,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 		kvm_vgic_flush_hwstate(vcpu);
 
-		/*
-		 * Exit if we have a signal pending so that we can deliver the
-		 * signal to user space.
-		 */
-		if (signal_pending(current)) {
-			ret = -EINTR;
-			run->exit_reason = KVM_EXIT_INTR;
-			++vcpu->stat.signal_exits;
-		}
-
-		/*
-		 * If we're using a userspace irqchip, then check if we need
-		 * to tell a userspace irqchip about timer or PMU level
-		 * changes and if so, exit to userspace (the actual level
-		 * state gets updated in kvm_timer_update_run and
-		 * kvm_pmu_update_run below).
-		 */
-		if (static_branch_unlikely(&userspace_irqchip_in_use)) {
-			if (kvm_timer_should_notify_user(vcpu) ||
-			    kvm_pmu_should_notify_user(vcpu)) {
-				ret = -EINTR;
-				run->exit_reason = KVM_EXIT_INTR;
-			}
-		}
-
 		/*
 		 * Ensure we set mode to IN_GUEST_MODE after we disable
 		 * interrupts and before the final VCPU requests check.
@@ -820,8 +837,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		 */
 		smp_store_mb(vcpu->mode, IN_GUEST_MODE);
 
-		if (ret <= 0 || need_new_vmid_gen(&vcpu->arch.hw_mmu->vmid) ||
-		    kvm_request_pending(vcpu)) {
+		if (ret <= 0 || kvm_vcpu_exit_request(vcpu, &ret)) {
 			vcpu->mode = OUTSIDE_GUEST_MODE;
 			isb(); /* Ensure work in x_flush_hwstate is committed */
 			kvm_pmu_sync_hwstate(vcpu);