x86/entry: Switch page fault exception to IDTENTRY_RAW

Convert page fault exceptions to IDTENTRY_RAW:

  - Implement the C entry point with DEFINE_IDTENTRY_RAW
  - Add the CR2 read into the exception handler
  - Add the idtentry_enter/exit_cond_rcu() invocations in
    in the regular page fault handler and in the async PF
    part.
  - Emit the ASM stub with DECLARE_IDTENTRY_RAW
  - Remove the ASM idtentry in 64-bit
  - Remove the CR2 read from 64-bit
  - Remove the open coded ASM entry code in 32-bit
  - Fix up the XEN/PV code
  - Remove the old prototypes

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202118.238455120@linutronix.de

1 files changed, 9 insertions, 6 deletions

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index d6f22a3a1f7d..d00f7c430e65 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -218,7 +218,7 @@ again:
 }
 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
 
-u32 kvm_read_and_reset_apf_flags(void)
+noinstr u32 kvm_read_and_reset_apf_flags(void)
 {
 	u32 flags = 0;
 
@@ -230,11 +230,11 @@ u32 kvm_read_and_reset_apf_flags(void)
 	return flags;
 }
 EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
-NOKPROBE_SYMBOL(kvm_read_and_reset_apf_flags);
 
-bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
+noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
 {
 	u32 reason = kvm_read_and_reset_apf_flags();
+	bool rcu_exit;
 
 	switch (reason) {
 	case KVM_PV_REASON_PAGE_NOT_PRESENT:
@@ -244,6 +244,9 @@ bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
 		return false;
 	}
 
+	rcu_exit = idtentry_enter_cond_rcu(regs);
+	instrumentation_begin();
+
 	/*
 	 * If the host managed to inject an async #PF into an interrupt
 	 * disabled region, then die hard as this is not going to end well
@@ -258,13 +261,13 @@ bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
 		/* Page is swapped out by the host. */
 		kvm_async_pf_task_wait_schedule(token);
 	} else {
-		rcu_irq_enter();
 		kvm_async_pf_task_wake(token);
-		rcu_irq_exit();
 	}
+
+	instrumentation_end();
+	idtentry_exit_cond_rcu(regs, rcu_exit);
 	return true;
 }
-NOKPROBE_SYMBOL(__kvm_handle_async_pf);
 
 static void __init paravirt_ops_setup(void)
 {