[tip: x86/cpu] x86/xen: Move Xen upcall handler to Xen specific code files

tip-bot2 for Brian Gerst
2025-03-14T09:47:02Z

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID: 827dc2e36172e978d6b1c701b04bee56881f54bf
Gitweb: https://git.kernel.org/tip/827dc2e36172e978d6b1c701b04bee56881f54bf
Author: Brian Gerst <brgerst@gmail.com>
AuthorDate: Thu, 13 Mar 2025 14:22:32 -04:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 14 Mar 2025 10:32:51 +01:00

x86/xen: Move Xen upcall handler to Xen specific code files

Move the upcall handler to Xen-specific files.

No functional changes.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20250313182236.655724-2-brgerst@gmail.com
---
arch/x86/entry/common.c | 72 +------------------------------------
arch/x86/xen/enlighten_pv.c | 46 +++++++++++++++++++++++-
include/xen/xen-ops.h | 19 ++++++++++-
3 files changed, 65 insertions(+), 72 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 3514bf2..ce4d88e 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -21,11 +21,6 @@
#include <linux/uaccess.h>
#include <linux/init.h>

-#ifdef CONFIG_XEN_PV
-#include <xen/xen-ops.h>
-#include <xen/events.h>
-#endif
-
#include <asm/apic.h>
#include <asm/desc.h>
#include <asm/traps.h>
@@ -455,70 +450,3 @@ SYSCALL_DEFINE0(ni_syscall)
{
return -ENOSYS;
}
-
-#ifdef CONFIG_XEN_PV
-#ifndef CONFIG_PREEMPTION
-/*
- * Some hypercalls issued by the toolstack can take many 10s of
- * seconds. Allow tasks running hypercalls via the privcmd driver to
- * be voluntarily preempted even if full kernel preemption is
- * disabled.
- *
- * Such preemptible hypercalls are bracketed by
- * xen_preemptible_hcall_begin() and xen_preemptible_hcall_end()
- * calls.
- */
-DEFINE_PER_CPU(bool, xen_in_preemptible_hcall);
-EXPORT_SYMBOL_GPL(xen_in_preemptible_hcall);
-
-/*
- * In case of scheduling the flag must be cleared and restored after
- * returning from schedule as the task might move to a different CPU.
- */
-static __always_inline bool get_and_clear_inhcall(void)
-{
- bool inhcall = __this_cpu_read(xen_in_preemptible_hcall);
-
- __this_cpu_write(xen_in_preemptible_hcall, false);
- return inhcall;
-}
-
-static __always_inline void restore_inhcall(bool inhcall)
-{
- __this_cpu_write(xen_in_preemptible_hcall, inhcall);
-}
-#else
-static __always_inline bool get_and_clear_inhcall(void) { return false; }
-static __always_inline void restore_inhcall(bool inhcall) { }
-#endif
-
-static void __xen_pv_evtchn_do_upcall(struct pt_regs *regs)
-{
- struct pt_regs *old_regs = set_irq_regs(regs);
-
- inc_irq_stat(irq_hv_callback_count);
-
- xen_evtchn_do_upcall();
-
- set_irq_regs(old_regs);
-}
-
-__visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs)
-{
- irqentry_state_t state = irqentry_enter(regs);
- bool inhcall;
-
- instrumentation_begin();
- run_sysvec_on_irqstack_cond(__xen_pv_evtchn_do_upcall, regs);
-
- inhcall = get_and_clear_inhcall();
- if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) {
- irqentry_exit_cond_resched();
- instrumentation_end();
- restore_inhcall(inhcall);
- } else {
- instrumentation_end();
- irqentry_exit(regs, state);
- }
-}
-#endif /* CONFIG_XEN_PV */
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 5e57835..af9e43c 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -73,6 +73,7 @@
#include <asm/mwait.h>
#include <asm/pci_x86.h>
#include <asm/cpu.h>
+#include <asm/irq_stack.h>
#ifdef CONFIG_X86_IOPL_IOPERM
#include <asm/io_bitmap.h>
#endif
@@ -94,6 +95,21 @@ void *xen_initial_gdt;
static int xen_cpu_up_prepare_pv(unsigned int cpu);
static int xen_cpu_dead_pv(unsigned int cpu);

+#ifndef CONFIG_PREEMPTION
+/*
+ * Some hypercalls issued by the toolstack can take many 10s of
+ * seconds. Allow tasks running hypercalls via the privcmd driver to
+ * be voluntarily preempted even if full kernel preemption is
+ * disabled.
+ *
+ * Such preemptible hypercalls are bracketed by
+ * xen_preemptible_hcall_begin() and xen_preemptible_hcall_end()
+ * calls.
+ */
+DEFINE_PER_CPU(bool, xen_in_preemptible_hcall);
+EXPORT_SYMBOL_GPL(xen_in_preemptible_hcall);
+#endif
+
struct tls_descs {
struct desc_struct desc[3];
};
@@ -687,6 +703,36 @@ DEFINE_IDTENTRY_RAW(xenpv_exc_machine_check)
}
#endif

+static void __xen_pv_evtchn_do_upcall(struct pt_regs *regs)
+{
+ struct pt_regs *old_regs = set_irq_regs(regs);
+
+ inc_irq_stat(irq_hv_callback_count);
+
+ xen_evtchn_do_upcall();
+
+ set_irq_regs(old_regs);
+}
+
+__visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs)
+{
+ irqentry_state_t state = irqentry_enter(regs);
+ bool inhcall;
+
+ instrumentation_begin();
+ run_sysvec_on_irqstack_cond(__xen_pv_evtchn_do_upcall, regs);
+
+ inhcall = get_and_clear_inhcall();
+ if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) {
+ irqentry_exit_cond_resched();
+ instrumentation_end();
+ restore_inhcall(inhcall);
+ } else {
+ instrumentation_end();
+ irqentry_exit(regs, state);
+ }
+}
+
struct trap_array_entry {
void (*orig)(void);
void (*xen)(void);
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index 47f11be..174ef8e 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -208,10 +208,29 @@ static inline void xen_preemptible_hcall_end(void)
__this_cpu_write(xen_in_preemptible_hcall, false);
}

+/*
+ * In case of scheduling the flag must be cleared and restored after
+ * returning from schedule as the task might move to a different CPU.
+ */
+static __always_inline bool get_and_clear_inhcall(void)
+{
+ bool inhcall = __this_cpu_read(xen_in_preemptible_hcall);
+
+ __this_cpu_write(xen_in_preemptible_hcall, false);
+ return inhcall;
+}
+
+static __always_inline void restore_inhcall(bool inhcall)
+{
+ __this_cpu_write(xen_in_preemptible_hcall, inhcall);
+}
+
#else

static inline void xen_preemptible_hcall_begin(void) { }
static inline void xen_preemptible_hcall_end(void) { }
+static __always_inline bool get_and_clear_inhcall(void) { return false; }
+static __always_inline void restore_inhcall(bool inhcall) { }

#endif /* CONFIG_XEN_PV && !CONFIG_PREEMPTION */