linux-kernel - [RFC PATCH 08/26] x86/paravirt: Stash native pv-ops

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Date:   Tue,  7 Apr 2020 22:03:05 -0700
From:   Ankur Arora <ankur.a.arora@...cle.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     peterz@...radead.org, hpa@...or.com, jpoimboe@...hat.com,
        namit@...are.com, mhiramat@...nel.org, jgross@...e.com,
        bp@...en8.de, vkuznets@...hat.com, pbonzini@...hat.com,
        boris.ostrovsky@...cle.com, mihai.carabas@...cle.com,
        kvm@...r.kernel.org, xen-devel@...ts.xenproject.org,
        virtualization@...ts.linux-foundation.org,
        Ankur Arora <ankur.a.arora@...cle.com>
Subject: [RFC PATCH 08/26] x86/paravirt: Stash native pv-ops

Introduce native_pv_ops where we stash the pv_ops array before
hypervisor specific hooks have modified it.

native_pv_ops get used when switching between paravirt and native
pv-ops at runtime.

Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
 arch/x86/include/asm/paravirt_types.h |  4 ++++
 arch/x86/kernel/paravirt.c            | 10 ++++++++++
 arch/x86/kernel/setup.c               |  2 ++
 3 files changed, 16 insertions(+)

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index f1153f53c529..bc935eec7ec6 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -339,6 +339,7 @@ extern struct paravirt_patch_template pv_ops;
 
 #ifdef CONFIG_PARAVIRT_RUNTIME
 #define PVRT_SUFFIX ".runtime"
+extern struct paravirt_patch_template native_pv_ops;
 #else
 #define PVRT_SUFFIX ""
 #endif
@@ -775,6 +776,9 @@ extern struct paravirt_patch_site __parainstructions[],
 #ifdef CONFIG_PARAVIRT_RUNTIME
 extern struct paravirt_patch_site __parainstructions_runtime[],
 	__parainstructions_runtime_end[];
+void paravirt_ops_init(void);
+#else
+static inline void paravirt_ops_init(void) { }
 #endif
 
 #endif	/* __ASSEMBLY__ */
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index c131ba4e70ef..8c511cc4d4f4 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -458,5 +458,15 @@ NOKPROBE_SYMBOL(native_set_debugreg);
 NOKPROBE_SYMBOL(native_load_idt);
 #endif
 
+#ifdef CONFIG_PARAVIRT_RUNTIME
+__ro_after_init struct paravirt_patch_template native_pv_ops;
+
+void __init paravirt_ops_init(void)
+{
+	native_pv_ops = pv_ops;
+}
+EXPORT_SYMBOL(native_pv_ops);
+#endif
+
 EXPORT_SYMBOL(pv_ops);
 EXPORT_SYMBOL_GPL(pv_info);
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index e6b545047f38..2746a6a78fe7 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -43,6 +43,7 @@
 #include <asm/unwind.h>
 #include <asm/vsyscall.h>
 #include <linux/vmalloc.h>
+#include <asm/paravirt_types.h>
 
 /*
  * max_low_pfn_mapped: highest directly mapped pfn < 4 GB
@@ -831,6 +832,7 @@ void __init setup_arch(char **cmdline_p)
 	boot_cpu_data.x86_phys_bits = MAX_PHYSMEM_BITS;
 #endif
 
+	paravirt_ops_init();
 	/*
 	 * If we have OLPC OFW, we might end up relocating the fixmap due to
 	 * reserve_top(), so do this before touching the ioremap area.
-- 
2.20.1