linux-kernel - [PATCH v4 01/11] x86/paravirt: Move halt paravirt calls under CONFIG

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Date:   Mon, 19 Jul 2021 17:40:47 -0700
From:   Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>
Cc:     Peter H Anvin <hpa@...or.com>, Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 01/11] x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT

From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>

CONFIG_PARAVIRT_XXL is mainly defined/used by XEN PV guests. For
other VM guest types, features supported under CONFIG_PARAVIRT
are self sufficient. CONFIG_PARAVIRT mainly provides support for
TLB flush operations and time related operations.

For TDX guest as well, paravirt calls under CONFIG_PARVIRT meets
most of its requirement except the need of HLT and SAFE_HLT
paravirt calls, which is currently defined under
COFNIG_PARAVIRT_XXL.

Since enabling CONFIG_PARAVIRT_XXL is too bloated for TDX guest
like platforms, move HLT and SAFE_HLT paravirt calls under
CONFIG_PARAVIRT.

Moving HLT and SAFE_HLT paravirt calls are not fatal and should not
break any functionality for current users of CONFIG_PARAVIRT.

Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Reviewed-by: Andi Kleen <ak@...ux.intel.com>
Reviewed-by: Tony Luck <tony.luck@...el.com>
---

Changes since v1:
 * None.

 arch/x86/include/asm/irqflags.h       | 40 +++++++++++++++------------
 arch/x86/include/asm/paravirt.h       | 20 +++++++-------
 arch/x86/include/asm/paravirt_types.h |  3 +-
 arch/x86/kernel/paravirt.c            |  4 ++-
 4 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index c5ce9845c999..f3bb33b1715d 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -59,6 +59,28 @@ static inline __cpuidle void native_halt(void)
 
 #endif
 
+#ifndef CONFIG_PARAVIRT
+#ifndef __ASSEMBLY__
+/*
+ * Used in the idle loop; sti takes one instruction cycle
+ * to complete:
+ */
+static inline __cpuidle void arch_safe_halt(void)
+{
+	native_safe_halt();
+}
+
+/*
+ * Used when interrupts are already enabled or to
+ * shutdown the processor:
+ */
+static inline __cpuidle void halt(void)
+{
+	native_halt();
+}
+#endif /* __ASSEMBLY__ */
+#endif /* CONFIG_PARAVIRT */
+
 #ifdef CONFIG_PARAVIRT_XXL
 #include <asm/paravirt.h>
 #else
@@ -80,24 +102,6 @@ static __always_inline void arch_local_irq_enable(void)
 	native_irq_enable();
 }
 
-/*
- * Used in the idle loop; sti takes one instruction cycle
- * to complete:
- */
-static inline __cpuidle void arch_safe_halt(void)
-{
-	native_safe_halt();
-}
-
-/*
- * Used when interrupts are already enabled or to
- * shutdown the processor:
- */
-static inline __cpuidle void halt(void)
-{
-	native_halt();
-}
-
 /*
  * For spinlocks, etc:
  */
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index da3a1ac82be5..d323a626c7a8 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -97,6 +97,16 @@ static inline void paravirt_arch_exit_mmap(struct mm_struct *mm)
 	PVOP_VCALL1(mmu.exit_mmap, mm);
 }
 
+static inline void arch_safe_halt(void)
+{
+	PVOP_VCALL0(irq.safe_halt);
+}
+
+static inline void halt(void)
+{
+	PVOP_VCALL0(irq.halt);
+}
+
 #ifdef CONFIG_PARAVIRT_XXL
 static inline void load_sp0(unsigned long sp0)
 {
@@ -162,16 +172,6 @@ static inline void __write_cr4(unsigned long x)
 	PVOP_VCALL1(cpu.write_cr4, x);
 }
 
-static inline void arch_safe_halt(void)
-{
-	PVOP_VCALL0(irq.safe_halt);
-}
-
-static inline void halt(void)
-{
-	PVOP_VCALL0(irq.halt);
-}
-
 static inline void wbinvd(void)
 {
 	PVOP_ALT_VCALL0(cpu.wbinvd, "wbinvd", ALT_NOT(X86_FEATURE_XENPV));
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index d9d6b0203ec4..40082847f314 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -150,10 +150,9 @@ struct pv_irq_ops {
 	struct paravirt_callee_save save_fl;
 	struct paravirt_callee_save irq_disable;
 	struct paravirt_callee_save irq_enable;
-
+#endif
 	void (*safe_halt)(void);
 	void (*halt)(void);
-#endif
 } __no_randomize_layout;
 
 struct pv_mmu_ops {
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 04cafc057bed..124e0f6c5d1c 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -283,9 +283,11 @@ struct paravirt_patch_template pv_ops = {
 	.irq.save_fl		= __PV_IS_CALLEE_SAVE(native_save_fl),
 	.irq.irq_disable	= __PV_IS_CALLEE_SAVE(native_irq_disable),
 	.irq.irq_enable		= __PV_IS_CALLEE_SAVE(native_irq_enable),
+#endif /* CONFIG_PARAVIRT_XXL */
+
+	/* Irq HLT ops. */
 	.irq.safe_halt		= native_safe_halt,
 	.irq.halt		= native_halt,
-#endif /* CONFIG_PARAVIRT_XXL */
 
 	/* Mmu ops. */
 	.mmu.flush_tlb_user	= native_flush_tlb_local,
-- 
2.25.1