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Subject[PATCH 1/4] paravirt: add generic _paravirt_false() function
Date
Add a _paravirt_false() default function returning always false which
can be used for cases where a boolean pvops replacement should just
say "no".

Signed-off-by: Juergen Gross <jgross@suse.com>
---
arch/x86/include/asm/paravirt_types.h | 2 ++
arch/x86/kernel/paravirt.c | 7 +++++++
arch/x86/kernel/paravirt_patch_32.c | 8 ++++++++
arch/x86/kernel/paravirt_patch_64.c | 7 +++++++
4 files changed, 24 insertions(+)

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 6b64fc6367f2..19efefc0e27e 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -377,6 +377,7 @@ extern struct pv_lock_ops pv_lock_ops;

unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len);
unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len);
+unsigned paravirt_patch_false(void *insnbuf, unsigned len);
unsigned paravirt_patch_call(void *insnbuf,
const void *target, u16 tgt_clobbers,
unsigned long addr, u16 site_clobbers,
@@ -682,6 +683,7 @@ void paravirt_flush_lazy_mmu(void);
void _paravirt_nop(void);
u32 _paravirt_ident_32(u32);
u64 _paravirt_ident_64(u64);
+bool _paravirt_false(void);

#define paravirt_nop ((void *)_paravirt_nop)

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index a14df9eecfed..94105773c00c 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -66,6 +66,11 @@ u64 notrace _paravirt_ident_64(u64 x)
return x;
}

+bool notrace _paravirt_false(void)
+{
+ return false;
+}
+
void __init default_banner(void)
{
printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
@@ -149,6 +154,8 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
ret = paravirt_patch_ident_32(insnbuf, len);
else if (opfunc == _paravirt_ident_64)
ret = paravirt_patch_ident_64(insnbuf, len);
+ else if (opfunc == _paravirt_false)
+ ret = paravirt_patch_false(insnbuf, len);

else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c
index 553acbbb4d32..287c7b9735de 100644
--- a/arch/x86/kernel/paravirt_patch_32.c
+++ b/arch/x86/kernel/paravirt_patch_32.c
@@ -9,6 +9,8 @@ DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax");
DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3");
DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax");

+DEF_NATIVE(, xor, "xor %eax, %eax");
+
#if defined(CONFIG_PARAVIRT_SPINLOCKS)
DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%eax)");
DEF_NATIVE(pv_lock_ops, vcpu_is_preempted, "xor %eax, %eax");
@@ -26,6 +28,12 @@ unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len)
return 0;
}

+unsigned paravirt_patch_false(void *insnbuf, unsigned len)
+{
+ return paravirt_patch_insns(insnbuf, len,
+ start__xor, end__xor);
+}
+
extern bool pv_is_native_spin_unlock(void);
extern bool pv_is_native_vcpu_is_preempted(void);

diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c
index 11aaf1eaa0e4..8ab4379ceea9 100644
--- a/arch/x86/kernel/paravirt_patch_64.c
+++ b/arch/x86/kernel/paravirt_patch_64.c
@@ -17,6 +17,7 @@ DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs");

DEF_NATIVE(, mov32, "mov %edi, %eax");
DEF_NATIVE(, mov64, "mov %rdi, %rax");
+DEF_NATIVE(, xor, "xor %rax, %rax");

#if defined(CONFIG_PARAVIRT_SPINLOCKS)
DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%rdi)");
@@ -35,6 +36,12 @@ unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len)
start__mov64, end__mov64);
}

+unsigned paravirt_patch_false(void *insnbuf, unsigned len)
+{
+ return paravirt_patch_insns(insnbuf, len,
+ start__xor, end__xor);
+}
+
extern bool pv_is_native_spin_unlock(void);
extern bool pv_is_native_vcpu_is_preempted(void);

--
2.12.3
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