This is necessary because on x86-64 struct vcpu_guest_context is larger
than PAGE_SIZE, and hence not suitable for a general purpose runtime
allocation. On x86-32, FIX_PAE_HIGHMEM_* fixmap entries are being
re-used, whiule on x86-64 new per-CPU fixmap entries get introduced.
The implication of using per-CPU fixmaps is that these allocations have
to happen from non-preemptable hypercall context (which they all do).
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -45,6 +45,7 @@
#include <asm/mpspec.h>
#include <asm/ldt.h>
#include <asm/hypercall.h>
+#include <asm/fixmap.h>
#include <asm/hvm/hvm.h>
#include <asm/hvm/support.h>
#include <asm/debugreg.h>
@@ -221,6 +222,53 @@ void free_vcpu_struct(struct vcpu *v)
free_xenheap_page(v);
}
+static DEFINE_PER_CPU(struct page_info *[
+ PFN_UP(sizeof(struct vcpu_guest_context))], vgc_pages);
+
+struct vcpu_guest_context *alloc_vcpu_guest_context(void)
+{
+ unsigned int i, cpu = smp_processor_id();
+ enum fixed_addresses idx = FIX_VGC_BEGIN -
+ cpu * PFN_UP(sizeof(struct vcpu_guest_context));
+
+#ifdef __i386__
+ BUILD_BUG_ON(sizeof(struct vcpu_guest_context) > PAGE_SIZE);
+#endif
+ BUG_ON(per_cpu(vgc_pages[0], cpu) != NULL);
+
+ for ( i = 0; i < PFN_UP(sizeof(struct vcpu_guest_context)); ++i )
+ {
+ struct page_info *pg = alloc_domheap_page(NULL, 0);
+
+ if ( unlikely(pg == NULL) )
+ {
+ free_vcpu_guest_context(NULL);
+ return NULL;
+ }
+ __set_fixmap(idx - i, page_to_mfn(pg), __PAGE_HYPERVISOR);
+ per_cpu(vgc_pages[i], cpu) = pg;
+ }
+ return (void *)fix_to_virt(idx);
+}
+
+void free_vcpu_guest_context(struct vcpu_guest_context *vgc)
+{
+ unsigned int i, cpu = smp_processor_id();
+ enum fixed_addresses idx = FIX_VGC_BEGIN -
+ cpu * PFN_UP(sizeof(struct vcpu_guest_context));
+
+ BUG_ON(vgc && vgc != (void *)fix_to_virt(idx));
+
+ for ( i = 0; i < PFN_UP(sizeof(struct vcpu_guest_context)); ++i )
+ {
+ if ( !per_cpu(vgc_pages[i], cpu) )
+ continue;
+ __set_fixmap(idx - i, 0, 0);
+ free_domheap_page(per_cpu(vgc_pages[i], cpu));
+ per_cpu(vgc_pages[i], cpu) = NULL;
+ }
+}
+
#ifdef __x86_64__
static int setup_compat_l4(struct vcpu *v)
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -832,12 +832,12 @@ long do_vcpu_op(int cmd, int vcpuid, XEN
if ( v->vcpu_info == &dummy_vcpu_info )
return -EINVAL;
- if ( (ctxt = xmalloc(struct vcpu_guest_context)) == NULL )
+ if ( (ctxt = alloc_vcpu_guest_context()) == NULL )
return -ENOMEM;
if ( copy_from_guest(ctxt, arg, 1) )
{
- xfree(ctxt);
+ free_vcpu_guest_context(ctxt);
return -EFAULT;
}
@@ -847,7 +847,7 @@ long do_vcpu_op(int cmd, int vcpuid, XEN
rc = boot_vcpu(d, vcpuid, ctxt);
domain_unlock(d);
- xfree(ctxt);
+ free_vcpu_guest_context(ctxt);
break;
case VCPUOP_up:
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -295,7 +295,7 @@ long do_domctl(XEN_GUEST_HANDLE(xen_domc
< sizeof(struct compat_vcpu_guest_context));
#endif
ret = -ENOMEM;
- if ( (c.nat = xmalloc(struct vcpu_guest_context)) == NULL )
+ if ( (c.nat = alloc_vcpu_guest_context()) == NULL )
goto svc_out;
#ifdef CONFIG_COMPAT
@@ -318,7 +318,7 @@ long do_domctl(XEN_GUEST_HANDLE(xen_domc
}
svc_out:
- xfree(c.nat);
+ free_vcpu_guest_context(c.nat);
rcu_unlock_domain(d);
}
break;
--- a/xen/include/asm-ia64/domain.h
+++ b/xen/include/asm-ia64/domain.h
@@ -25,6 +25,9 @@ struct vcpu;
extern void relinquish_vcpu_resources(struct vcpu *v);
extern int vcpu_late_initialise(struct vcpu *v);
+#define alloc_vcpu_guest_context() xmalloc(struct vcpu_guest_context)
+#define free_vcpu_guest_context(vgc) xfree(vgc)
+
/* given a current domain metaphysical address, return the physical address */
extern unsigned long translate_domain_mpaddr(unsigned long mpaddr,
struct p2m_entry* entry);
--- a/xen/include/asm-x86/fixmap.h
+++ b/xen/include/asm-x86/fixmap.h
@@ -16,6 +16,7 @@
#include <asm/apicdef.h>
#include <asm/acpi.h>
#include <asm/page.h>
+#include <xen/pfn.h>
#include <xen/kexec.h>
#include <xen/iommu.h>
#include <asm/amd-iommu.h>
@@ -34,6 +35,12 @@ enum fixed_addresses {
#ifdef __i386__
FIX_PAE_HIGHMEM_0,
FIX_PAE_HIGHMEM_END = FIX_PAE_HIGHMEM_0 + NR_CPUS-1,
+#define FIX_VGC_END FIX_PAE_HIGHMEM_0
+#define FIX_VGC_BEGIN FIX_PAE_HIGHMEM_END
+#else
+ FIX_VGC_END,
+ FIX_VGC_BEGIN = FIX_VGC_END
+ + PFN_UP(sizeof(struct vcpu_guest_context)) * NR_CPUS - 1,
#endif
FIX_APIC_BASE,
FIX_IO_APIC_BASE_0,
--- a/xen/include/xen/domain.h
+++ b/xen/include/xen/domain.h
@@ -32,6 +32,12 @@ void free_domain_struct(struct domain *d
struct vcpu *alloc_vcpu_struct(void);
void free_vcpu_struct(struct vcpu *v);
+/* Allocate/free a vcpu_guest_context structure. */
+#ifndef alloc_vcpu_guest_context
+struct vcpu_guest_context *alloc_vcpu_guest_context(void);
+void free_vcpu_guest_context(struct vcpu_guest_context *);
+#endif
+
/*
* Initialise/destroy arch-specific details of a VCPU.
* - vcpu_initialise() is called after the basic generic fields of the
x86-alloc-vcpu-guest-context.patch
Description: Text document
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