[RFC v1 01/26] x86/paravirt: Introduce CONFIG_PARAVIRT_XL

[Kuppuswamy Sathyanarayanan]

From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>

Split off halt paravirt calls from CONFIG_PARAVIRT_XXL into
a separate config option. It provides a middle ground for
not-so-deep paravirtulized environments.

CONFIG_PARAVIRT_XL will be used by TDX that needs couple of paravirt
calls that was hidden under CONFIG_PARAVIRT_XXL, but the rest of the
config would be a bloat for TDX.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---
 arch/x86/Kconfig                      |  4 +++
 arch/x86/boot/compressed/misc.h       |  1 +
 arch/x86/include/asm/irqflags.h       | 42 +++++++++++++++------------
 arch/x86/include/asm/paravirt.h       | 22 +++++++-------
 arch/x86/include/asm/paravirt_types.h |  3 +-
 arch/x86/kernel/paravirt.c            |  4 ++-
 arch/x86/mm/mem_encrypt_identity.c    |  1 +
 7 files changed, 46 insertions(+), 31 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7b6dd10b162a..8fe91114bfee 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -776,8 +776,12 @@ config PARAVIRT
 	  over full virtualization.  However, when run without a hypervisor
 	  the kernel is theoretically slower and slightly larger.
 
+config PARAVIRT_XL
+	bool
+
 config PARAVIRT_XXL
 	bool
+	select PARAVIRT_XL
 
 config PARAVIRT_DEBUG
 	bool "paravirt-ops debugging"
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 901ea5ebec22..4b84abe43765 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -9,6 +9,7 @@
  * paravirt and debugging variants are added.)
  */
 #undef CONFIG_PARAVIRT
+#undef CONFIG_PARAVIRT_XL
 #undef CONFIG_PARAVIRT_XXL
 #undef CONFIG_PARAVIRT_SPINLOCKS
 #undef CONFIG_KASAN
diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index 2dfc8d380dab..299c9b1ed857 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -68,11 +68,33 @@ static inline __cpuidle void native_halt(void)
 
 #endif
 
-#ifdef CONFIG_PARAVIRT_XXL
+#ifdef CONFIG_PARAVIRT_XL
 #include <asm/paravirt.h>
 #else
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
+/*
+ * 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_XL */
+
+#ifndef CONFIG_PARAVIRT_XXL
+#ifndef __ASSEMBLY__
 
 static __always_inline unsigned long arch_local_save_flags(void)
 {
@@ -94,24 +116,6 @@ 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 f8dce11d2bc1..700b94abfd1b 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -84,6 +84,18 @@ static inline void paravirt_arch_exit_mmap(struct mm_struct *mm)
 	PVOP_VCALL1(mmu.exit_mmap, mm);
 }
 
+#ifdef CONFIG_PARAVIRT_XL
+static inline void arch_safe_halt(void)
+{
+	PVOP_VCALL0(irq.safe_halt);
+}
+
+static inline void halt(void)
+{
+	PVOP_VCALL0(irq.halt);
+}
+#endif
+
 #ifdef CONFIG_PARAVIRT_XXL
 static inline void load_sp0(unsigned long sp0)
 {
@@ -145,16 +157,6 @@ 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_VCALL0(cpu.wbinvd);
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index b6b02b7c19cc..634482a0a60d 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -190,7 +190,8 @@ struct pv_irq_ops {
 	struct paravirt_callee_save restore_fl;
 	struct paravirt_callee_save irq_disable;
 	struct paravirt_callee_save irq_enable;
-
+#endif
+#ifdef CONFIG_PARAVIRT_XL
 	void (*safe_halt)(void);
 	void (*halt)(void);
 #endif
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 6c3407ba6ee9..85714a6389d6 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -327,9 +327,11 @@ struct paravirt_patch_template pv_ops = {
 	.irq.restore_fl		= __PV_IS_CALLEE_SAVE(native_restore_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 */
+#ifdef CONFIG_PARAVIRT_XL
 	.irq.safe_halt		= native_safe_halt,
 	.irq.halt		= native_halt,
-#endif /* CONFIG_PARAVIRT_XXL */
+#endif /* CONFIG_PARAVIRT_XL */
 
 	/* Mmu ops. */
 	.mmu.flush_tlb_user	= native_flush_tlb_local,
diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index 6c5eb6f3f14f..20d0cb116557 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -24,6 +24,7 @@
  * be extended when new paravirt and debugging variants are added.)
  */
 #undef CONFIG_PARAVIRT
+#undef CONFIG_PARAVIRT_XL
 #undef CONFIG_PARAVIRT_XXL
 #undef CONFIG_PARAVIRT_SPINLOCKS
 
-- 
2.25.1