daed39e878
checked in (request 35384) OBS-URL: https://build.opensuse.org/request/show/35384 OBS-URL: https://build.opensuse.org/package/show/Virtualization/xen?expand=0&rev=36
67 lines
2.9 KiB
Diff
67 lines
2.9 KiB
Diff
In domain_create, previously we reserve 1M memory for domain creation (as
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described in xend comment), and these memory SHOULD NOT related with vcpu
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number. And later, shadow_mem_control() will modify the shadow size to 256
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pages per vcpu (also plus some other values related with guest memory size...).
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Therefore the C/S 20389 which modifies 1M to 4M to fit more vcpu number is
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wrong. I'm sorry for that.
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Following is the reason why currently 1M doesn't work for big number vcpus,
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as we mentioned, it caused Xen crash.
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Each time when sh_set_allocation() is called, it checks whether
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shadow_min_acceptable_pages() has been allocated, if not, it will allocate
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them. That is to say, it is 128 pages per vcpu. But before we define
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d->max_vcpu, guest vcpu hasn't been initialized, so
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shadow_min_acceptable_pages() always returns 0. Therefore we only allocated 1M
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shadow memory for domain_create, and didn't satisfy 128 pages per vcpu for
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alloc_vcpu().
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As we know, vcpu allocation is done in the hypercall of
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XEN_DOMCTL_max_vcpus. However, at this point we haven't called
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shadow_mem_control() and are still using the pre-allocated 1M shadow memory to
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allocate so many vcpus. So it should be a BUG. Therefore when vcpu number
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increases, 1M is not enough and causes Xen crash. C/S 20389 exposes this issue.
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So I think the right process should be, after d->max_vcpu is set and before
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alloc_vcpu(), we should call sh_set_allocation() to satisfy 128 pages per vcpu.
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The following patch does this work. Is it work for you? Thanks!
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Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
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Index: xen-4.0.0-testing/xen/arch/x86/mm/shadow/common.c
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===================================================================
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--- xen-4.0.0-testing.orig/xen/arch/x86/mm/shadow/common.c
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+++ xen-4.0.0-testing/xen/arch/x86/mm/shadow/common.c
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@@ -41,6 +41,9 @@
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DEFINE_PER_CPU(uint32_t,trace_shadow_path_flags);
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+static unsigned int sh_set_allocation(struct domain *d,
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+ unsigned int pages,
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+ int *preempted);
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/* Set up the shadow-specific parts of a domain struct at start of day.
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* Called for every domain from arch_domain_create() */
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void shadow_domain_init(struct domain *d, unsigned int domcr_flags)
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@@ -82,6 +85,12 @@ void shadow_vcpu_init(struct vcpu *v)
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}
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#endif
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+ if ( !is_idle_domain(v->domain) )
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+ {
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+ shadow_lock(v->domain);
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+ sh_set_allocation(v->domain, 128, NULL);
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+ shadow_unlock(v->domain);
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+ }
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v->arch.paging.mode = &SHADOW_INTERNAL_NAME(sh_paging_mode, 3);
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}
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@@ -3102,7 +3111,7 @@ int shadow_enable(struct domain *d, u32
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{
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unsigned int r;
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shadow_lock(d);
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- r = sh_set_allocation(d, 1024, NULL); /* Use at least 4MB */
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+ r = sh_set_allocation(d, 256, NULL); /* Use at least 1MB */
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if ( r != 0 )
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{
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sh_set_allocation(d, 0, NULL);
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