[tip: x86/urgent] x86/tdx: Fix early #VE handling

[tip-bot2 for Kirill A. Shutemov]

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

Commit-ID:     60428d8bc27f52e8f1540f98e1b6ef0156d43f0d
Gitweb:        https://git.kernel.org/tip/60428d8bc27f52e8f1540f98e1b6ef0156d43f0d
Author:        Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
AuthorDate:    Tue, 14 Jun 2022 15:01:33 +03:00
Committer:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Wed, 15 Jun 2022 10:52:59 -07:00

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: 32e72854fa5f ("x86/tdx: Port I/O: Add early boot support")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20220614120135.14812-2-kirill.shutemov@xxxxxxxxxxxxxxx
---
 arch/x86/coco/tdx/tdx.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 03deb4d..faae53f 100644
--- 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)