[xen staging] x86/IDT: Fix IDT generation for INT $0x80

[patchbot@xxxxxxx]

commit 7323c93b2af24b3373f4934989988f8e47bb8ea4
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Tue Mar 11 21:13:33 2025 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Wed Mar 12 09:25:04 2025 +0000

    x86/IDT: Fix IDT generation for INT $0x80
    
    When PV is enabled, entry_int80 needs to be DPL3, not DPL0.
    
    This, combined with a QEMU bug which incorrectly calculates the error
    code (fix submitted separately), causes the XSA-259 PoC to fail with:
    
      --- Xen Test Framework ---
      Environment: PV 64bit (Long mode 4 levels)
      XSA-259 PoC
      Error: Unexpected fault 0x800d0802, #GP[IDT[256]]
      Test result: ERROR
    
    Fixes: 3da2149cf4dc ("x86/IDT: Generate bsp_idt[] at build time")
    Reported-by: Luca Fancellu <luca.fancellu@xxxxxxx>
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Tested-by: Luca Fancellu <luca.fancellu@xxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/include/asm/gen-idt.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/include/asm/gen-idt.h 
b/xen/arch/x86/include/asm/gen-idt.h
index 9c8810edf9..d1da73248c 100644
--- a/xen/arch/x86/include/asm/gen-idt.h
+++ b/xen/arch/x86/include/asm/gen-idt.h
@@ -77,7 +77,7 @@ GEN16(6);
 GEN16(7);
 
 #ifdef CONFIG_PV
-GEN(0x80, entry_int80,      DPL0, manual);
+GEN(0x80, entry_int80,      DPL3, manual);
 #else
 GEN(0x80, entry_0x80,       DPL0, autogen);
 #endif
--
generated by git-patchbot for /home/xen/git/xen.git#staging