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>,
Juergen Gross <jgross@suse.com>,
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 V7 5/6] x86/entry: Don't call error_entry() for XENPV
Date: Tue, 3 May 2022 11:21:06 +0800 [thread overview]
Message-ID: <20220503032107.680190-6-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20220503032107.680190-1-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.
Cc: Juergen Gross <jgross@suse.com>
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 ab6ab6d3dab5..062aa9d95961 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -336,8 +336,17 @@ SYM_CODE_END(push_and_clear_regs)
call push_and_clear_regs
UNWIND_HINT_REGS
- 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:[~2022-05-03 3:21 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-03 3:21 [PATCH V7 0/6] x86/entry: Clean up entry code Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 1/6] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2022-05-03 19:01 ` [tip: x86/asm] x86/traps: Use pt_regs directly " tip-bot2 for Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 2/6] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2022-05-03 19:01 ` [tip: x86/asm] " tip-bot2 for Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 3/6] x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry() Lai Jiangshan
2022-05-03 7:23 ` Juergen Gross
2022-05-03 19:01 ` [tip: x86/asm] " tip-bot2 for Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 4/6] x86/entry: Move cld to the start of idtentry macro Lai Jiangshan
2022-05-03 19:01 ` [tip: x86/asm] x86/entry: Move CLD to the start of the " tip-bot2 for Lai Jiangshan
2022-05-03 3:21 ` Lai Jiangshan [this message]
2022-05-03 7:24 ` [PATCH V7 5/6] x86/entry: Don't call error_entry() for XENPV Juergen Gross
2022-05-03 19:01 ` [tip: x86/asm] " tip-bot2 for Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 6/6] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS Lai Jiangshan
2022-05-03 19:01 ` [tip: x86/asm] " tip-bot2 for Lai Jiangshan
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