[PATCH 5.10 141/294] x86/entry_32: Add VERW just before userspace transition

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5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>

commit a0e2dab44d22b913b4c228c8b52b2a104434b0b3 upstream.

As done for entry_64, add support for executing VERW late in exit to
user path for 32-bit mode.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20240213-delay-verw-v8-3-a6216d83edb7%40linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/x86/entry/entry_32.S |    3 +++
 1 file changed, 3 insertions(+)

--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -949,6 +949,7 @@ SYM_FUNC_START(entry_SYSENTER_32)
 	BUG_IF_WRONG_CR3 no_user_check=1
 	popfl
 	popl	%eax
+	CLEAR_CPU_BUFFERS
 
 	/*
 	 * Return back to the vDSO, which will pop ecx and edx.
@@ -1021,6 +1022,7 @@ restore_all_switch_stack:
 
 	/* Restore user state */
 	RESTORE_REGS pop=4			# skip orig_eax/error_code
+	CLEAR_CPU_BUFFERS
 .Lirq_return:
 	/*
 	 * ARCH_HAS_MEMBARRIER_SYNC_CORE rely on IRET core serialization
@@ -1219,6 +1221,7 @@ SYM_CODE_START(asm_exc_nmi)
 
 	/* Not on SYSENTER stack. */
 	call	exc_nmi
+	CLEAR_CPU_BUFFERS
 	jmp	.Lnmi_return
 
 .Lnmi_from_sysenter_stack:






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