[PATCH 1/3] x86: provide an init_mem_mapping hypervisor hook

From: Juergen Gross
Date: Tue Jul 25 2017 - 05:50:30 EST


Provide a hook in hypervisor_x86 called after setting up initial
memory mapping.

This is needed e.g. by Xen HVM guests to map the hypervisor shared
info page.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
arch/x86/include/asm/hypervisor.h | 10 ++++++++++
arch/x86/mm/init.c | 3 +++
2 files changed, 13 insertions(+)

diff --git a/arch/x86/include/asm/hypervisor.h b/arch/x86/include/asm/hypervisor.h
index 21126155a739..60ebda5e5101 100644
--- a/arch/x86/include/asm/hypervisor.h
+++ b/arch/x86/include/asm/hypervisor.h
@@ -43,6 +43,9 @@ struct hypervisor_x86 {

/* pin current vcpu to specified physical cpu (run rarely) */
void (*pin_vcpu)(int);
+
+ /* called during init_mem_mapping() to setup early mappings. */
+ void (*init_mem_mapping)(void);
};

extern const struct hypervisor_x86 *x86_hyper;
@@ -57,8 +60,15 @@ extern const struct hypervisor_x86 x86_hyper_kvm;
extern void init_hypervisor_platform(void);
extern bool hypervisor_x2apic_available(void);
extern void hypervisor_pin_vcpu(int cpu);
+
+static inline void hypervisor_init_mem_mapping(void)
+{
+ if (x86_hyper->init_mem_mapping)
+ x86_hyper->init_mem_mapping();
+}
#else
static inline void init_hypervisor_platform(void) { }
static inline bool hypervisor_x2apic_available(void) { return false; }
+static inline void hypervisor_init_mem_mapping(void) { }
#endif /* CONFIG_HYPERVISOR_GUEST */
#endif /* _ASM_X86_HYPERVISOR_H */
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 673541eb3b3f..bf3f1065d6ad 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -18,6 +18,7 @@
#include <asm/dma.h> /* for MAX_DMA_PFN */
#include <asm/microcode.h>
#include <asm/kaslr.h>
+#include <asm/hypervisor.h>

/*
* We need to define the tracepoints somewhere, and tlb.c
@@ -636,6 +637,8 @@ void __init init_mem_mapping(void)
load_cr3(swapper_pg_dir);
__flush_tlb_all();

+ hypervisor_init_mem_mapping();
+
early_memtest(0, max_pfn_mapped << PAGE_SHIFT);
}

--
2.12.3