[SRU][N:linux-gcp][PATCH 1/2] x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT

[Ian Whitfield]

From: "Kirill A. Shutemov" <kirill.shutemov at linux.intel.com>

BugLink: https://bugs.launchpad.net/bugs/2112602

commit 22cc5ca5de52bbfc36a7d4a55323f91fb4492264 upstream.

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
CONFIG_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.

Fixes: bfe6ed0c6727 ("x86/tdx: Add HLT support for TDX guests")
Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy at linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy at linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov at linux.intel.com>
Signed-off-by: Vishal Annapurve <vannapurve at google.com>
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Reviewed-by: Andi Kleen <ak at linux.intel.com>
Reviewed-by: Tony Luck <tony.luck at intel.com>
Reviewed-by: Juergen Gross <jgross at suse.com>
Tested-by: Ryan Afranji <afranji at google.com>
Cc: Andy Lutomirski <luto at kernel.org>
Cc: Brian Gerst <brgerst at gmail.com>
Cc: H. Peter Anvin <hpa at zytor.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe at redhat.com>
Cc: stable at kernel.org
Link: https://lore.kernel.org/r/20250228014416.3925664-2-vannapurve@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit 8d25a8e275bb0b74fe84367e83f23bf8fc0de5ce linux-6.6.y)
Signed-off-by: Ian Whitfield <ian.whitfield at canonical.com>
---
 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            | 14 ++++++----
 4 files changed, 41 insertions(+), 36 deletions(-)

diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index 8c5ae649d2df..9acfe2bcf1fd 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -56,6 +56,28 @@ static __always_inline void native_halt(void)
 
 #endif
 
+#ifndef CONFIG_PARAVIRT
+#ifndef __ASSEMBLY__
+/*
+ * Used in the idle loop; sti takes one instruction cycle
+ * to complete:
+ */
+static __always_inline void arch_safe_halt(void)
+{
+	native_safe_halt();
+}
+
+/*
+ * Used when interrupts are already enabled or to
+ * shutdown the processor:
+ */
+static __always_inline void halt(void)
+{
+	native_halt();
+}
+#endif /* __ASSEMBLY__ */
+#endif /* CONFIG_PARAVIRT */
+
 #ifdef CONFIG_PARAVIRT_XXL
 #include <asm/paravirt.h>
 #else
@@ -77,24 +99,6 @@ 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 __always_inline void arch_safe_halt(void)
-{
-	native_safe_halt();
-}
-
-/*
- * Used when interrupts are already enabled or to
- * shutdown the processor:
- */
-static __always_inline 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 d4eb9e1d61b8..75d4c994f5e2 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -107,6 +107,16 @@ static inline void notify_page_enc_status_changed(unsigned long pfn,
 	PVOP_VCALL3(mmu.notify_page_enc_status_changed, pfn, npages, enc);
 }
 
+static __always_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)
 {
@@ -170,16 +180,6 @@ static inline void __write_cr4(unsigned long x)
 	PVOP_VCALL1(cpu.write_cr4, x);
 }
 
-static __always_inline void arch_safe_halt(void)
-{
-	PVOP_VCALL0(irq.safe_halt);
-}
-
-static inline void halt(void)
-{
-	PVOP_VCALL0(irq.halt);
-}
-
 extern noinstr void pv_native_wbinvd(void);
 
 static __always_inline void wbinvd(void)
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 8d4fbe1be489..9334fdd1f635 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -122,10 +122,9 @@ 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 fec381533555..edaa74c311c8 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -100,6 +100,11 @@ int paravirt_disable_iospace(void)
 	return request_resource(&ioport_resource, &reserve_ioports);
 }
 
+static noinstr void pv_native_safe_halt(void)
+{
+	native_safe_halt();
+}
+
 #ifdef CONFIG_PARAVIRT_XXL
 static noinstr void pv_native_write_cr2(unsigned long val)
 {
@@ -120,11 +125,6 @@ noinstr void pv_native_wbinvd(void)
 {
 	native_wbinvd();
 }
-
-static noinstr void pv_native_safe_halt(void)
-{
-	native_safe_halt();
-}
 #endif
 
 struct pv_info pv_info = {
@@ -182,9 +182,11 @@ struct paravirt_patch_template pv_ops = {
 	.irq.save_fl		= __PV_IS_CALLEE_SAVE(pv_native_save_fl),
 	.irq.irq_disable	= __PV_IS_CALLEE_SAVE(pv_native_irq_disable),
 	.irq.irq_enable		= __PV_IS_CALLEE_SAVE(pv_native_irq_enable),
+#endif /* CONFIG_PARAVIRT_XXL */
+
+	/* Irq HLT ops. */
 	.irq.safe_halt		= pv_native_safe_halt,
 	.irq.halt		= native_halt,
-#endif /* CONFIG_PARAVIRT_XXL */
 
 	/* Mmu ops. */
 	.mmu.flush_tlb_user	= native_flush_tlb_local,
-- 
2.43.0