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-rw-r--r--include/linux/entry-kvm.h80
-rw-r--r--include/linux/kvm_host.h8
-rw-r--r--kernel/entry/Makefile3
-rw-r--r--kernel/entry/kvm.c51
-rw-r--r--virt/kvm/Kconfig3
5 files changed, 144 insertions, 1 deletions
diff --git a/include/linux/entry-kvm.h b/include/linux/entry-kvm.h
new file mode 100644
index 000000000000..0cef17afb41a
--- /dev/null
+++ b/include/linux/entry-kvm.h
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_ENTRYKVM_H
+#define __LINUX_ENTRYKVM_H
+
+#include <linux/entry-common.h>
+
+/* Transfer to guest mode work */
+#ifdef CONFIG_KVM_XFER_TO_GUEST_WORK
+
+#ifndef ARCH_XFER_TO_GUEST_MODE_WORK
+# define ARCH_XFER_TO_GUEST_MODE_WORK (0)
+#endif
+
+#define XFER_TO_GUEST_MODE_WORK \
+ (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
+ _TIF_NOTIFY_RESUME | ARCH_XFER_TO_GUEST_MODE_WORK)
+
+struct kvm_vcpu;
+
+/**
+ * arch_xfer_to_guest_mode_handle_work - Architecture specific xfer to guest
+ * mode work handling function.
+ * @vcpu: Pointer to current's VCPU data
+ * @ti_work: Cached TIF flags gathered in xfer_to_guest_mode_handle_work()
+ *
+ * Invoked from xfer_to_guest_mode_handle_work(). Defaults to NOOP. Can be
+ * replaced by architecture specific code.
+ */
+static inline int arch_xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu,
+ unsigned long ti_work);
+
+#ifndef arch_xfer_to_guest_mode_work
+static inline int arch_xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu,
+ unsigned long ti_work)
+{
+ return 0;
+}
+#endif
+
+/**
+ * xfer_to_guest_mode_handle_work - Check and handle pending work which needs
+ * to be handled before going to guest mode
+ * @vcpu: Pointer to current's VCPU data
+ *
+ * Returns: 0 or an error code
+ */
+int xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu);
+
+/**
+ * __xfer_to_guest_mode_work_pending - Check if work is pending
+ *
+ * Returns: True if work pending, False otherwise.
+ *
+ * Bare variant of xfer_to_guest_mode_work_pending(). Can be called from
+ * interrupt enabled code for racy quick checks with care.
+ */
+static inline bool __xfer_to_guest_mode_work_pending(void)
+{
+ unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
+
+ return !!(ti_work & XFER_TO_GUEST_MODE_WORK);
+}
+
+/**
+ * xfer_to_guest_mode_work_pending - Check if work is pending which needs to be
+ * handled before returning to guest mode
+ *
+ * Returns: True if work pending, False otherwise.
+ *
+ * Has to be invoked with interrupts disabled before the transition to
+ * guest mode.
+ */
+static inline bool xfer_to_guest_mode_work_pending(void)
+{
+ lockdep_assert_irqs_disabled();
+ return __xfer_to_guest_mode_work_pending();
+}
+#endif /* CONFIG_KVM_XFER_TO_GUEST_WORK */
+
+#endif
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d564855243d8..ac83e9c1d82c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1439,4 +1439,12 @@ int kvm_vm_create_worker_thread(struct kvm *kvm, kvm_vm_thread_fn_t thread_fn,
uintptr_t data, const char *name,
struct task_struct **thread_ptr);
+#ifdef CONFIG_KVM_XFER_TO_GUEST_WORK
+static inline void kvm_handle_signal_exit(struct kvm_vcpu *vcpu)
+{
+ vcpu->run->exit_reason = KVM_EXIT_INTR;
+ vcpu->stat.signal_exits++;
+}
+#endif /* CONFIG_KVM_XFER_TO_GUEST_WORK */
+
#endif
diff --git a/kernel/entry/Makefile b/kernel/entry/Makefile
index c207d202bf3a..34c8a3f1c735 100644
--- a/kernel/entry/Makefile
+++ b/kernel/entry/Makefile
@@ -9,4 +9,5 @@ KCOV_INSTRUMENT := n
CFLAGS_REMOVE_common.o = -fstack-protector -fstack-protector-strong
CFLAGS_common.o += -fno-stack-protector
-obj-$(CONFIG_GENERIC_ENTRY) += common.o
+obj-$(CONFIG_GENERIC_ENTRY) += common.o
+obj-$(CONFIG_KVM_XFER_TO_GUEST_WORK) += kvm.o
diff --git a/kernel/entry/kvm.c b/kernel/entry/kvm.c
new file mode 100644
index 000000000000..eb1a8a4c867c
--- /dev/null
+++ b/kernel/entry/kvm.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/entry-kvm.h>
+#include <linux/kvm_host.h>
+
+static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work)
+{
+ do {
+ int ret;
+
+ if (ti_work & _TIF_SIGPENDING) {
+ kvm_handle_signal_exit(vcpu);
+ return -EINTR;
+ }
+
+ if (ti_work & _TIF_NEED_RESCHED)
+ schedule();
+
+ if (ti_work & _TIF_NOTIFY_RESUME) {
+ clear_thread_flag(TIF_NOTIFY_RESUME);
+ tracehook_notify_resume(NULL);
+ }
+
+ ret = arch_xfer_to_guest_mode_handle_work(vcpu, ti_work);
+ if (ret)
+ return ret;
+
+ ti_work = READ_ONCE(current_thread_info()->flags);
+ } while (ti_work & XFER_TO_GUEST_MODE_WORK || need_resched());
+ return 0;
+}
+
+int xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu)
+{
+ unsigned long ti_work;
+
+ /*
+ * This is invoked from the outer guest loop with interrupts and
+ * preemption enabled.
+ *
+ * KVM invokes xfer_to_guest_mode_work_pending() with interrupts
+ * disabled in the inner loop before going into guest mode. No need
+ * to disable interrupts here.
+ */
+ ti_work = READ_ONCE(current_thread_info()->flags);
+ if (!(ti_work & XFER_TO_GUEST_MODE_WORK))
+ return 0;
+
+ return xfer_to_guest_mode_work(vcpu, ti_work);
+}
+EXPORT_SYMBOL_GPL(xfer_to_guest_mode_handle_work);
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index aad9284c043a..1c37ccd5d402 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -60,3 +60,6 @@ config HAVE_KVM_VCPU_RUN_PID_CHANGE
config HAVE_KVM_NO_POLL
bool
+
+config KVM_XFER_TO_GUEST_WORK
+ bool

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