From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, Lai Jiangshan <jiangshan.ljs@antgroup.com>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH V5 5/7] x86/entry: Don't call error_entry() for XENPV
Date: Tue, 12 Apr 2022 20:15:39 +0800 [thread overview]
Message-ID: <20220412121541.4595-6-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20220412121541.4595-1-jiangshanlai@gmail.com>
From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
When in XENPV, it is already in the task stack, and it can't fault for
native_iret() nor native_load_gs_index() since XENPV uses its own pvops
for IRET and load_gs_index(). And it doesn't need to switch the CR3.
So there is no reason to call error_entry() in XENPV.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
arch/x86/entry/entry_64.S | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 7b6a0f15bb20..3aca7815fe79 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -328,8 +328,17 @@ SYM_CODE_END(ret_from_fork)
PUSH_AND_CLEAR_REGS
ENCODE_FRAME_POINTER
- call error_entry
- movq %rax, %rsp /* switch to the task stack if from userspace */
+ /*
+ * Call error_entry() and switch to the task stack if from userspace.
+ *
+ * When in XENPV, it is already in the task stack, and it can't fault
+ * for native_iret() nor native_load_gs_index() since XENPV uses its
+ * own pvops for IRET and load_gs_index(). And it doesn't need to
+ * switch the CR3. So it can skip invoking error_entry().
+ */
+ ALTERNATIVE "call error_entry; movq %rax, %rsp", \
+ "", X86_FEATURE_XENPV
+
ENCODE_FRAME_POINTER
UNWIND_HINT_REGS
--
2.19.1.6.gb485710b
next prev parent reply other threads:[~2022-04-12 12:47 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-12 12:15 [PATCH V5 0/7] x86/entry: Clean up entry code Lai Jiangshan
2022-04-12 12:15 ` [PATCH V5 1/7] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2022-04-12 12:15 ` [PATCH V5 2/7] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2022-04-12 12:15 ` [PATCH V5 3/7] x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry() Lai Jiangshan
2022-04-12 13:26 ` Borislav Petkov
2022-04-12 13:52 ` Lai Jiangshan
2022-04-12 14:30 ` Borislav Petkov
2022-04-13 3:48 ` Lai Jiangshan
2022-04-13 8:39 ` Borislav Petkov
2022-04-12 12:15 ` [PATCH V5 4/7] x86/entry: Move cld to the start of idtentry macro Lai Jiangshan
2022-04-12 12:15 ` Lai Jiangshan [this message]
2022-04-20 16:32 ` [PATCH V5 5/7] x86/entry: Don't call error_entry() for XENPV Borislav Petkov
2022-04-12 12:15 ` [PATCH V5 6/7] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS Lai Jiangshan
2022-04-12 12:15 ` [PATCH V5 7/7] x86/entry: Use idtentry macro for entry_INT80_compat Lai Jiangshan
2022-04-25 10:24 ` Thomas Gleixner
2022-04-25 13:25 ` Lai Jiangshan
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