Re: [Xen-devel] [PATCH v4 06/18] x86/mem_sharing: define mem_sharing_domain to hold some scattered variables

2020-01-16 Thread Jan Beulich
On 16.01.2020 17:05, Tamas K Lengyel wrote:
> On Thu, Jan 16, 2020 at 8:23 AM Jan Beulich  wrote:
>>
>> On 08.01.2020 18:14, Tamas K Lengyel wrote:
>>> Create struct mem_sharing_domain under hvm_domain and move mem sharing
>>> variables into it from p2m_domain and hvm_domain.
>>>
>>> Expose the mem_sharing_enabled macro to be used consistently across Xen.
>>>
>>> Remove some duplicate calls to mem_sharing_enabled in mem_sharing.c
>>>
>>> Signed-off-by: Tamas K Lengyel 
>>
>> Acked-by: Jan Beulich 
>> with one question:
>>
>>> @@ -192,6 +192,10 @@ struct hvm_domain {
>>>  struct vmx_domain vmx;
>>>  struct svm_domain svm;
>>>  };
>>> +
>>> +#ifdef CONFIG_MEM_SHARING
>>> +struct mem_sharing_domain mem_sharing;
>>> +#endif
>>
>> Are you intending to add fields to this new struct? If so,
>> should the field here become a pointer, and the structure
>> allocated only when actually needed?
>>
> 
> At the moment there are no additional variables planned to be added.
> If/when we do we can consider turning this into a pointer, at which
> point we can also get rid of the "enabled" field and turn the
> mem_sharing_enabled macro into a NULL-pointer check instead. For now I
> wouldn't bother because its not like we save much by doing so.

Thanks for clarifying.

Jan

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Re: [Xen-devel] [PATCH v4 06/18] x86/mem_sharing: define mem_sharing_domain to hold some scattered variables

2020-01-16 Thread Tamas K Lengyel
On Thu, Jan 16, 2020 at 8:23 AM Jan Beulich  wrote:
>
> On 08.01.2020 18:14, Tamas K Lengyel wrote:
> > Create struct mem_sharing_domain under hvm_domain and move mem sharing
> > variables into it from p2m_domain and hvm_domain.
> >
> > Expose the mem_sharing_enabled macro to be used consistently across Xen.
> >
> > Remove some duplicate calls to mem_sharing_enabled in mem_sharing.c
> >
> > Signed-off-by: Tamas K Lengyel 
>
> Acked-by: Jan Beulich 
> with one question:
>
> > @@ -192,6 +192,10 @@ struct hvm_domain {
> >  struct vmx_domain vmx;
> >  struct svm_domain svm;
> >  };
> > +
> > +#ifdef CONFIG_MEM_SHARING
> > +struct mem_sharing_domain mem_sharing;
> > +#endif
>
> Are you intending to add fields to this new struct? If so,
> should the field here become a pointer, and the structure
> allocated only when actually needed?
>

At the moment there are no additional variables planned to be added.
If/when we do we can consider turning this into a pointer, at which
point we can also get rid of the "enabled" field and turn the
mem_sharing_enabled macro into a NULL-pointer check instead. For now I
wouldn't bother because its not like we save much by doing so.

Thanks,
Tamas

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Re: [Xen-devel] [PATCH v4 06/18] x86/mem_sharing: define mem_sharing_domain to hold some scattered variables

2020-01-16 Thread Jan Beulich
On 08.01.2020 18:14, Tamas K Lengyel wrote:
> Create struct mem_sharing_domain under hvm_domain and move mem sharing
> variables into it from p2m_domain and hvm_domain.
> 
> Expose the mem_sharing_enabled macro to be used consistently across Xen.
> 
> Remove some duplicate calls to mem_sharing_enabled in mem_sharing.c
> 
> Signed-off-by: Tamas K Lengyel 

Acked-by: Jan Beulich 
with one question:

> @@ -192,6 +192,10 @@ struct hvm_domain {
>  struct vmx_domain vmx;
>  struct svm_domain svm;
>  };
> +
> +#ifdef CONFIG_MEM_SHARING
> +struct mem_sharing_domain mem_sharing;
> +#endif

Are you intending to add fields to this new struct? If so,
should the field here become a pointer, and the structure
allocated only when actually needed?

Jan

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[Xen-devel] [PATCH v4 06/18] x86/mem_sharing: define mem_sharing_domain to hold some scattered variables

2020-01-08 Thread Tamas K Lengyel
Create struct mem_sharing_domain under hvm_domain and move mem sharing
variables into it from p2m_domain and hvm_domain.

Expose the mem_sharing_enabled macro to be used consistently across Xen.

Remove some duplicate calls to mem_sharing_enabled in mem_sharing.c

Signed-off-by: Tamas K Lengyel 
---
 xen/arch/x86/mm/mem_sharing.c | 10 --
 xen/drivers/passthrough/pci.c |  3 +--
 xen/include/asm-x86/hvm/domain.h  |  6 +-
 xen/include/asm-x86/mem_sharing.h | 16 
 xen/include/asm-x86/p2m.h |  4 
 5 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index f6187403a0..3aa61c30e6 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -197,9 +197,6 @@ static shr_handle_t get_next_handle(void)
 return x + 1;
 }
 
-#define mem_sharing_enabled(d) \
-(is_hvm_domain(d) && (d)->arch.hvm.mem_sharing_enabled)
-
 static atomic_t nr_saved_mfns   = ATOMIC_INIT(0);
 static atomic_t nr_shared_mfns  = ATOMIC_INIT(0);
 
@@ -1309,6 +1306,7 @@ int __mem_sharing_unshare_page(struct domain *d,
 int relinquish_shared_pages(struct domain *d)
 {
 int rc = 0;
+struct mem_sharing_domain *msd = >arch.hvm.mem_sharing;
 struct p2m_domain *p2m = p2m_get_hostp2m(d);
 unsigned long gfn, count = 0;
 
@@ -1316,7 +1314,7 @@ int relinquish_shared_pages(struct domain *d)
 return 0;
 
 p2m_lock(p2m);
-for ( gfn = p2m->next_shared_gfn_to_relinquish;
+for ( gfn = msd->next_shared_gfn_to_relinquish;
   gfn <= p2m->max_mapped_pfn; gfn++ )
 {
 p2m_access_t a;
@@ -1351,7 +1349,7 @@ int relinquish_shared_pages(struct domain *d)
 {
 if ( hypercall_preempt_check() )
 {
-p2m->next_shared_gfn_to_relinquish = gfn + 1;
+msd->next_shared_gfn_to_relinquish = gfn + 1;
 rc = -ERESTART;
 break;
 }
@@ -1437,7 +1435,7 @@ int 
mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
 
 /* Only HAP is supported */
 rc = -ENODEV;
-if ( !hap_enabled(d) || !d->arch.hvm.mem_sharing_enabled )
+if ( !mem_sharing_enabled(d) )
 goto out;
 
 switch ( mso.op )
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index c07a63981a..65d1d457ff 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -1498,8 +1498,7 @@ static int assign_device(struct domain *d, u16 seg, u8 
bus, u8 devfn, u32 flag)
 /* Prevent device assign if mem paging or mem sharing have been 
  * enabled for this domain */
 if ( d != dom_io &&
- unlikely((is_hvm_domain(d) &&
-   d->arch.hvm.mem_sharing_enabled) ||
+ unlikely(mem_sharing_enabled(d) ||
   vm_event_check_ring(d->vm_event_paging) ||
   p2m_get_hostp2m(d)->global_logdirty) )
 return -EXDEV;
diff --git a/xen/include/asm-x86/hvm/domain.h b/xen/include/asm-x86/hvm/domain.h
index bcc5621797..8f70ba2b1a 100644
--- a/xen/include/asm-x86/hvm/domain.h
+++ b/xen/include/asm-x86/hvm/domain.h
@@ -29,6 +29,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -156,7 +157,6 @@ struct hvm_domain {
 
 struct viridian_domain *viridian;
 
-bool_t mem_sharing_enabled;
 bool_t qemu_mapcache_invalidate;
 bool_t is_s3_suspended;
 
@@ -192,6 +192,10 @@ struct hvm_domain {
 struct vmx_domain vmx;
 struct svm_domain svm;
 };
+
+#ifdef CONFIG_MEM_SHARING
+struct mem_sharing_domain mem_sharing;
+#endif
 };
 
 #endif /* __ASM_X86_HVM_DOMAIN_H__ */
diff --git a/xen/include/asm-x86/mem_sharing.h 
b/xen/include/asm-x86/mem_sharing.h
index cf7848709f..13114b6346 100644
--- a/xen/include/asm-x86/mem_sharing.h
+++ b/xen/include/asm-x86/mem_sharing.h
@@ -26,6 +26,20 @@
 
 #ifdef CONFIG_MEM_SHARING
 
+struct mem_sharing_domain
+{
+bool enabled;
+
+/*
+ * When releasing shared gfn's in a preemptible manner, recall where
+ * to resume the search.
+ */
+unsigned long next_shared_gfn_to_relinquish;
+};
+
+#define mem_sharing_enabled(d) \
+(hap_enabled(d) && (d)->arch.hvm.mem_sharing.enabled)
+
 /* Auditing of memory sharing code? */
 #ifndef NDEBUG
 #define MEM_SHARING_AUDIT 1
@@ -104,6 +118,8 @@ int relinquish_shared_pages(struct domain *d);
 
 #else
 
+#define mem_sharing_enabled(d) false
+
 static inline unsigned int mem_sharing_get_nr_saved_mfns(void)
 {
 return 0;
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 7399c4a897..8defa90306 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -305,10 +305,6 @@ struct p2m_domain {
 unsigned long min_remapped_gfn;
 unsigned long max_remapped_gfn;
 
-/* When releasing shared gfn's in a preemptible manner, recall where
- * to resume the search */
-