[xen master] x86/traps: Make an IDT-specific #PF helper

[patchbot@xxxxxxx]

commit 4153eb7660ad441de75ab6dca50b54eb340d0728
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Mon Aug 11 12:42:01 2025 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Fri Dec 5 23:00:32 2025 +0000

    x86/traps: Make an IDT-specific #PF helper
    
    FRED provides %cr2 in the the stack frame, avoiding the need to read %cr2
    manually.
    
    Rename do_page_fault() to handle_PF(), and update it to take cr2, still 
named
    addr for consistency.
    
    Introduce a new handle_PF_IDT() which reads %cr2 and conditionally 
re-enables
    interrupts.
    
    No functional change.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/traps.c        | 26 ++++++++++++++------------
 xen/arch/x86/x86_64/entry.S |  2 +-
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 3f1eae0d40..6ba7ae5202 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -1676,21 +1676,10 @@ static int fixup_page_fault(unsigned long addr, struct 
cpu_user_regs *regs)
     return 0;
 }
 
-void asmlinkage do_page_fault(struct cpu_user_regs *regs)
+static void handle_PF(struct cpu_user_regs *regs, unsigned long addr /* cr2 */)
 {
-    unsigned long addr;
     unsigned int error_code;
 
-    addr = read_cr2();
-
-    /*
-     * Don't re-enable interrupts if we were running an IRQ-off region when
-     * we hit the page fault, or we'll break that code.
-     */
-    ASSERT(!local_irq_is_enabled());
-    if ( regs->flags & X86_EFLAGS_IF )
-        local_irq_enable();
-
     /* fixup_page_fault() might change regs->error_code, so cache it here. */
     error_code = regs->error_code;
 
@@ -1751,6 +1740,19 @@ void asmlinkage do_page_fault(struct cpu_user_regs *regs)
     pv_inject_page_fault(regs->error_code, addr);
 }
 
+/*
+ * When using IDT delivery, it is our responsibility to read %cr2.
+ */
+void asmlinkage handle_PF_IDT(struct cpu_user_regs *regs)
+{
+    unsigned long addr = read_cr2();
+
+    if ( regs->flags & X86_EFLAGS_IF )
+        local_irq_enable();
+
+    handle_PF(regs, addr);
+}
+
 /*
  * Early #PF handler to print CR2, error code, and stack.
  *
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 789687488c..c02245ac06 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -871,7 +871,7 @@ handle_exception_saved:
          * reading %cr2. Otherwise a page fault in the nested interrupt handler
          * would corrupt %cr2.
          */
-        DISPATCH(X86_EXC_PF, do_page_fault)
+        DISPATCH(X86_EXC_PF, handle_PF_IDT)
 
         /* Only re-enable IRQs if they were active before taking the fault */
         testb $X86_EFLAGS_IF >> 8, UREGS_eflags + 1(%rsp)
--
generated by git-patchbot for /home/xen/git/xen.git#master