x86/tdx: Fix early #VE handling

tdx_early_handle_ve() does not increment RIP after successfully
handling the exception.  That leads to infinite loop of exceptions.

Move RIP when exceptions are successfully handled.

[ dhansen: make problem statement more clear ]

Fixes: b57980532319 ("x86/tdx: Port I/O: Add early boot support")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Link: https://lkml.kernel.org/r/20220614120135.14812-2-kirill.shutemov@linux.intel.com

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 03deb4d6920d552b79f4654da5fe531baa3157d1..faae53f8d55954cee9bda35d742b3ffb05dce627 100644 (file)
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -447,13 +447,17 @@ static bool handle_io(struct pt_regs *regs, u32 exit_qual)
 __init bool tdx_early_handle_ve(struct pt_regs *regs)
 {
        struct ve_info ve;
+       bool ret;
 
        tdx_get_ve_info(&ve);
 
        if (ve.exit_reason != EXIT_REASON_IO_INSTRUCTION)
                return false;
 
-       return handle_io(regs, ve.exit_qual);
+       ret = handle_io(regs, ve.exit_qual);
+       if (ret)
+               regs->ip += ve.instr_len;
+       return ret;
 }
 
 void tdx_get_ve_info(struct ve_info *ve)