[PATCH v7 1/3] x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT - Linux-stable-mirror

28 Feb 2025

From: "Kirill A. Shutemov" kirill.shutemov@linux.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
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.
Cc: stable@vger.kernel.org
Fixes: bfe6ed0c6727 ("x86/tdx: Add HLT support for TDX guests")
Co-developed-by: Kuppuswamy Sathyanarayanan sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Kuppuswamy Sathyanarayanan sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com
Reviewed-by: Andi Kleen ak@linux.intel.com
Reviewed-by: Tony Luck tony.luck@intel.com
Reviewed-by: Juergen Gross jgross@suse.com
Signed-off-by: Vishal Annapurve vannapurve@google.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 cf7fc2b8e3ce..1c2db11a2c3c 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -76,6 +76,28 @@ static __always_inline void native_local_irq_restore(unsigned long flags)
#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
@@ -97,24 +119,6 @@ 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 041aff51eb50..29e7331a0c98 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);
-}
-
 static inline u64 paravirt_read_msr(unsigned msr)
 {
    return PVOP_CALL1(u64, cpu.read_msr, msr);
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index fea56b04f436..abccfccc2e3f 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -120,10 +120,9 @@ 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 1ccaa3397a67..c5bb980b8a67 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -110,6 +110,11 @@ 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)
 {
@@ -125,11 +130,6 @@ static noinstr void pv_native_set_debugreg(int regno, unsigned long val)
 {
    native_set_debugreg(regno, val);
 }
-
-static noinstr void pv_native_safe_halt(void)
-{
-	native_safe_halt();
-}
 #endif
struct pv_info pv_info = {
@@ -186,9 +186,11 @@ 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,
-- 
2.48.1.711.g2feabab25a-goog



    