Re: [PATCH v2] x86/paravirt: use common macro for creating simple asm paravirt functions

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On 16.11.22 12:04, Peter Zijlstra wrote:
On Wed, Nov 09, 2022 at 02:44:18PM +0100, Juergen Gross wrote:
There are some paravirt assembler functions which are sharing a common
pattern. Introduce a macro DEFINE_PARAVIRT_ASM() for creating them.

Note that this macro is including explicit alignment of the generated
functions, leading to __raw_callee_save___kvm_vcpu_is_preempted(),
_paravirt_nop() and paravirt_ret0() to be aligned at 4 byte boundaries
now.

The explicit _paravirt_nop() prototype in paravirt.c isn't needed, as
it is included in paravirt_types.h already.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Srivatsa S. Bhat (VMware) <srivatsa@xxxxxxxxxxxxx>
---

Seems nice; I've made the below little edits, but this is certainly a
bit large for /urgent at this point in time. So how about I merge
locking/urgent into x86/paravirt and munge this on top?

Fine with me.

Thanks for looking at the patch,


Juergen


---
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -737,7 +737,7 @@ static __always_inline unsigned long arc
  	     __ALIGN_STR "\n"				\
  	     #func ":\n\t"				\
  	     ASM_ENDBR					\
-	     instr					\
+	     instr "\n\t"				\
  	     ASM_RET					\
  	     ".size " #func ", . - " #func "\n\t"	\
  	     ".popsection")
--- a/arch/x86/include/asm/qspinlock_paravirt.h
+++ b/arch/x86/include/asm/qspinlock_paravirt.h
@@ -54,8 +54,8 @@ __PV_CALLEE_SAVE_REGS_THUNK(__pv_queued_
  	"pop    %rdx\n\t"						\
  	FRAME_END
-DEFINE_PARAVIRT_ASM(__raw_callee_save___pv_queued_spin_unlock, PV_UNLOCK_ASM,
-		    .spinlock.text);
+DEFINE_PARAVIRT_ASM(__raw_callee_save___pv_queued_spin_unlock,
+		    PV_UNLOCK_ASM, .spinlock.text);
#else /* CONFIG_64BIT */ --- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -802,6 +802,7 @@ extern bool __raw_callee_save___kvm_vcpu
   "movq   __per_cpu_offset(,%rdi,8), %rax\n\t"				     \
   "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax)\n\t" \
   "setne  %al\n\t"
+
  DEFINE_PARAVIRT_ASM(__raw_callee_save___kvm_vcpu_is_preempted,
  		    PV_VCPU_PREEMPTED_ASM, .text);
  #endif
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -40,8 +40,7 @@
  DEFINE_PARAVIRT_ASM(_paravirt_nop, "", .entry.text);
/* stub always returning 0. */
-#define PV_RET0_ASM	"xor %" _ASM_AX ", %" _ASM_AX "\n\t"
-DEFINE_PARAVIRT_ASM(paravirt_ret0, PV_RET0_ASM, .entry.text);
+DEFINE_PARAVIRT_ASM(paravirt_ret0, "xor %eax,%eax", .entry.text);
void __init default_banner(void)
  {

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