From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Lai Jiangshan <jiangshan.ljs@antgroup.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH V3 6/7] x86/entry: Don't call error_entry for XENPV
Date: Tue, 15 Mar 2022 15:39:48 +0800 [thread overview]
Message-ID: <20220315073949.7541-7-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20220315073949.7541-1-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 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 e4a07276fd1c..ec885c2107de 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 stack settled by sync_regs() */
+ /*
+ * Call error_entry and switch stack settled by sync_regs().
+ *
+ * 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 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:[~2022-03-15 7:40 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-15 7:39 [PATCH V3 0/7] x86/entry: Clean up entry code Lai Jiangshan
2022-03-15 7:39 ` [PATCH V3 1/7] x86/entry: Use idtentry macro for entry_INT80_compat Lai Jiangshan
2022-03-16 13:48 ` Peter Zijlstra
2022-03-15 7:39 ` [PATCH V3 2/7] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2022-03-15 7:39 ` [PATCH V3 3/7] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2022-03-16 2:37 ` Josh Poimboeuf
2022-03-16 3:02 ` Lai Jiangshan
2022-03-16 15:05 ` Peter Zijlstra
2022-03-16 16:43 ` Lai Jiangshan
2022-03-18 11:12 ` Peter Zijlstra
2022-03-15 7:39 ` [PATCH V3 4/7] x86/entry: move PUSH_AND_CLEAR_REGS out of error_entry Lai Jiangshan
2022-03-16 15:07 ` Peter Zijlstra
2022-03-16 16:18 ` Lai Jiangshan
2022-03-15 7:39 ` [PATCH V3 5/7] x86/entry: Move cld to the start of idtentry Lai Jiangshan
2022-03-15 7:39 ` Lai Jiangshan [this message]
2022-03-16 2:59 ` [PATCH V3 6/7] x86/entry: Don't call error_entry for XENPV Josh Poimboeuf
2022-03-16 15:09 ` Peter Zijlstra
2022-03-16 16:48 ` Lai Jiangshan
2022-03-15 7:39 ` [PATCH V3 7/7] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS Lai Jiangshan
2022-03-16 15:12 ` [PATCH V3 0/7] x86/entry: Clean up entry code Peter Zijlstra
2022-03-16 15:13 ` Peter Zijlstra
2022-03-17 12:58 ` Lai Jiangshan
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