From 3e8ea7803a1dedf19120a2fef12c590e90e4b469 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 10 Nov 2021 11:01:17 +0100 Subject: [PATCH] x86/vmx: Remove .fixup usage In the vmread exceptin path, use the, thus far, unused output register to push the @fault argument onto the stack. This, in turn, enables the exception handler to not do pushes and only modify that register when an exception does occur. As noted by Sean the input constraint needs to be changed to "=&r" to avoid the value and field occupying the same register. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Paolo Bonzini Reviewed-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20211110101325.781308550@infradead.org --- arch/x86/kvm/vmx/vmx_ops.h | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h index 9e9ef47e988c..35d9324c2f2a 100644 --- a/arch/x86/kvm/vmx/vmx_ops.h +++ b/arch/x86/kvm/vmx/vmx_ops.h @@ -80,9 +80,11 @@ static __always_inline unsigned long __vmcs_readl(unsigned long field) * @field, and bounce through the trampoline to preserve * volatile registers. */ - "push $0\n\t" + "xorl %k1, %k1\n\t" + "2:\n\t" + "push %1\n\t" "push %2\n\t" - "2:call vmread_error_trampoline\n\t" + "call vmread_error_trampoline\n\t" /* * Unwind the stack. Note, the trampoline zeros out the @@ -93,13 +95,9 @@ static __always_inline unsigned long __vmcs_readl(unsigned long field) "3:\n\t" /* VMREAD faulted. As above, except push '1' for @fault. */ - ".pushsection .fixup, \"ax\"\n\t" - "4: push $1\n\t" - "push %2\n\t" - "jmp 2b\n\t" - ".popsection\n\t" - _ASM_EXTABLE(1b, 4b) - : ASM_CALL_CONSTRAINT, "=r"(value) : "r"(field) : "cc"); + _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_ONE_REG, %1) + + : ASM_CALL_CONSTRAINT, "=&r"(value) : "r"(field) : "cc"); return value; } -- GitLab