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

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  [PATCH 1/3] x86: provide an init_mem_mapping hypervisor hook Juergen Gross <jgross@suse.com> - 2017-07-25 12:00 +0200
    Re: [PATCH 1/3] x86: provide an init_mem_mapping hypervisor hook Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-07-25 16:10 +0200
      Re: [PATCH 1/3] x86: provide an init_mem_mapping hypervisor hook Juergen Gross <jgross@suse.com> - 2017-07-26 09:50 +0200

#1695555 — [PATCH 1/3] x86: provide an init_mem_mapping hypervisor hook

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@suse.com>
---
 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

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#1695767

On 07/25/2017 05:50 AM, Juergen Gross wrote:
> 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.

This is not necessarily a problem specific to guests so I wonder whether
the hook should be part of x86_platform_ops or some other x86 structure.

-boris

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#1696849

On 25/07/17 16:09, Boris Ostrovsky wrote:
> On 07/25/2017 05:50 AM, Juergen Gross wrote:
>> 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.
> 
> This is not necessarily a problem specific to guests so I wonder whether
> the hook should be part of x86_platform_ops or some other x86 structure.

I'm fine with any solution. I've chosen the hypervisor struct as right
now there seems to be a need for HVM Xen guests only.


Juergen

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