[PATCH 2/2] x86/paravirt: Introduce CONFIG_PARAVIRT_HLT

[Kirill A. Shutemov]

CONFIG_PARAVIRT_FULL provides a way to hook up the full set of paravirt
ops, but TDX only needs two of them: halt() and safe_halt().

Split off halt paravirt calls from CONFIG_PARAVIRT_FULL into
a separate config option -- CONFIG_PARAVIRT_HLT.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 arch/x86/Kconfig                      |  4 +++
 arch/x86/boot/compressed/misc.h       |  1 +
 arch/x86/include/asm/irqflags.h       | 38 +++++++++++++++------------
 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, 44 insertions(+), 29 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 568b96e20d59..830367e36d5a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -783,8 +783,12 @@ config PARAVIRT
 	  over full virtualization.  However, when run without a hypervisor
 	  the kernel is theoretically slower and slightly larger.
 
+config PARAVIRT_HLT
+	bool
+
 config PARAVIRT_FULL
 	bool
+	select PARAVIRT_HLT
 
 config PARAVIRT_DEBUG
 	bool "paravirt-ops debugging"
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 0e5713c1cb86..293f22dbada4 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_HLT
 #undef CONFIG_PARAVIRT_FULL
 #undef CONFIG_PARAVIRT_SPINLOCKS
 #undef CONFIG_KASAN
diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index a4d7dbc2b034..ae839e74fc34 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -59,27 +59,11 @@ static inline __cpuidle void native_halt(void)
 
 #endif
 
-#ifdef CONFIG_PARAVIRT_FULL
+#ifdef CONFIG_PARAVIRT_HLT
 #include <asm/paravirt.h>
 #else
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
-
-static __always_inline unsigned long arch_local_save_flags(void)
-{
-	return native_save_fl();
-}
-
-static __always_inline void arch_local_irq_disable(void)
-{
-	native_irq_disable();
-}
-
-static __always_inline void arch_local_irq_enable(void)
-{
-	native_irq_enable();
-}
-
 /*
  * Used in the idle loop; sti takes one instruction cycle
  * to complete:
@@ -97,6 +81,26 @@ static inline __cpuidle void halt(void)
 {
 	native_halt();
 }
+#endif /* !__ASSEMBLY__ */
+#endif /* CONFIG_PARAVIRT_HLT */
+
+#ifndef CONFIG_PARAVIRT_FULL
+#ifndef __ASSEMBLY__
+
+static __always_inline unsigned long arch_local_save_flags(void)
+{
+	return native_save_fl();
+}
+
+static __always_inline void arch_local_irq_disable(void)
+{
+	native_irq_disable();
+}
+
+static __always_inline void arch_local_irq_enable(void)
+{
+	native_irq_enable();
+}
 
 /*
  * For spinlocks, etc:
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 02751519b0d9..6bc5c1eab6eb 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_HLT
+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_FULL
 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 ae3503b2e8a2..cac32ffd95ca 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -177,7 +177,8 @@ struct pv_irq_ops {
 	struct paravirt_callee_save save_fl;
 	struct paravirt_callee_save irq_disable;
 	struct paravirt_callee_save irq_enable;
-
+#endif
+#ifdef CONFIG_PARAVIRT_HLT
 	void (*safe_halt)(void);
 	void (*halt)(void);
 #endif
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index e3a5f0cf9340..752fc3ab81bf 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -322,9 +322,11 @@ 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_FULL */
+#ifdef CONFIG_PARAVIRT_HLT
 	.irq.safe_halt		= native_safe_halt,
 	.irq.halt		= native_halt,
-#endif /* CONFIG_PARAVIRT_FULL */
+#endif /* CONFIG_PARAVIRT_HLT */
 
 	/* 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 53fe895cefe2..7cb9b70edbe7 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_HLT
 #undef CONFIG_PARAVIRT_FULL
 #undef CONFIG_PARAVIRT_SPINLOCKS
 
-- 
2.26.3


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