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[PATCH v4 3/4] xen: move alloc/free_vcpu_struct() to common code



alloc_vcpu_struct() and free_vcpu_struct() contain little
architecture-specific logic and are suitable for sharing across
architectures. Move both helpers to common code.

To support the remaining architectural differences, introduce
arch_vcpu_struct_memflags(), allowing architectures to override the
memory flags passed to alloc_xenheap_pages(). This is currently needed
by x86, which may require MEMF_bits(32) for HVM guests using shadow
paging.

The ARM implementation of alloc/free_vcpu_struct() is removed and
replaced by the common version. Stub implementations are also dropped
from PPC and RISC-V.

Now that the size of struct vcpu for Arm64 is smaller than PAGE_SIZE,
MAX_PAGES_PER_VCPU is no longer needed and is removed.

Finally, make alloc_vcpu_struct() and free_vcpu_struct() static to
common/domain.c, as they are no longer used outside common code.

No functional changes.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
Changes in v4:
 - Move implementation of alloc_vcpu_struct() and free_vcpu_struct() ahead
   of vmtrace_free_buffer().
 - Add Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>.
 - Add Acked-by: Jan Beulich <jbeulich@xxxxxxxx>.
---
Changes in v3:
 - Make from function arch_vcpu_struct_memflags() a macros in asm/domain.h.
 - Drop forward declaration of arch_vcpu_struct_memflags() in asm/domain.h.
 - Update defintion of arch_vcpu_stuct_memflags() in alloc_vcpu_struct().
---
Changes in v2:
 - Rework alloc/free_vcpu_struct() to work with only one page.
 - Return back the comment about the restriction inside x86's
   arch_vcpu_struct_memflags().
 - Drop MAX_PAGES_PER_VCPU.
---
 xen/arch/arm/domain.c             | 32 -------------------------------
 xen/arch/ppc/stubs.c              | 10 ----------
 xen/arch/riscv/stubs.c            | 10 ----------
 xen/arch/x86/domain.c             | 24 -----------------------
 xen/arch/x86/include/asm/domain.h | 12 ++++++++++++
 xen/common/domain.c               | 20 +++++++++++++++++++
 xen/include/xen/domain.h          |  4 ----
 7 files changed, 32 insertions(+), 80 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 47973f99d935..507df807edb8 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -473,38 +473,6 @@ void dump_pageframe_info(struct domain *d)
 
 }
 
-/*
- * The new VGIC has a bigger per-IRQ structure, so we need more than one
- * page on ARM64. Cowardly increase the limit in this case.
- */
-#if defined(CONFIG_NEW_VGIC) && defined(CONFIG_ARM_64)
-#define MAX_PAGES_PER_VCPU  2
-#else
-#define MAX_PAGES_PER_VCPU  1
-#endif
-
-struct vcpu *alloc_vcpu_struct(const struct domain *d)
-{
-    struct vcpu *v;
-
-    BUILD_BUG_ON(sizeof(*v) > MAX_PAGES_PER_VCPU * PAGE_SIZE);
-    v = alloc_xenheap_pages(get_order_from_bytes(sizeof(*v)), 0);
-    if ( v != NULL )
-    {
-        unsigned int i;
-
-        for ( i = 0; i < DIV_ROUND_UP(sizeof(*v), PAGE_SIZE); i++ )
-            clear_page((void *)v + i * PAGE_SIZE);
-    }
-
-    return v;
-}
-
-void free_vcpu_struct(struct vcpu *v)
-{
-    free_xenheap_pages(v, get_order_from_bytes(sizeof(*v)));
-}
-
 int arch_vcpu_create(struct vcpu *v)
 {
     int rc = 0;
diff --git a/xen/arch/ppc/stubs.c b/xen/arch/ppc/stubs.c
index 9953ea1c6c08..f7f6e7ed97af 100644
--- a/xen/arch/ppc/stubs.c
+++ b/xen/arch/ppc/stubs.c
@@ -152,11 +152,6 @@ void dump_pageframe_info(struct domain *d)
     BUG_ON("unimplemented");
 }
 
-void free_vcpu_struct(struct vcpu *v)
-{
-    BUG_ON("unimplemented");
-}
-
 int arch_vcpu_create(struct vcpu *v)
 {
     BUG_ON("unimplemented");
@@ -264,11 +259,6 @@ void vcpu_kick(struct vcpu *v)
     BUG_ON("unimplemented");
 }
 
-struct vcpu *alloc_vcpu_struct(const struct domain *d)
-{
-    BUG_ON("unimplemented");
-}
-
 unsigned long
 hypercall_create_continuation(unsigned int op, const char *format, ...)
 {
diff --git a/xen/arch/riscv/stubs.c b/xen/arch/riscv/stubs.c
index 164fc091b28a..29bdb65afbdf 100644
--- a/xen/arch/riscv/stubs.c
+++ b/xen/arch/riscv/stubs.c
@@ -121,11 +121,6 @@ void dump_pageframe_info(struct domain *d)
     BUG_ON("unimplemented");
 }
 
-void free_vcpu_struct(struct vcpu *v)
-{
-    BUG_ON("unimplemented");
-}
-
 int arch_vcpu_create(struct vcpu *v)
 {
     BUG_ON("unimplemented");
@@ -233,11 +228,6 @@ void vcpu_kick(struct vcpu *v)
     BUG_ON("unimplemented");
 }
 
-struct vcpu *alloc_vcpu_struct(const struct domain *d)
-{
-    BUG_ON("unimplemented");
-}
-
 unsigned long
 hypercall_create_continuation(unsigned int op, const char *format, ...)
 {
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 7632d5e2d62d..c29a6b0decee 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -493,30 +493,6 @@ unsigned int arch_domain_struct_memflags(void)
     return MEMF_bits(bits);
 }
 
-struct vcpu *alloc_vcpu_struct(const struct domain *d)
-{
-    struct vcpu *v;
-    /*
-     * This structure contains embedded PAE PDPTEs, used when an HVM guest
-     * runs on shadow pagetables outside of 64-bit mode. In this case the CPU
-     * may require that the shadow CR3 points below 4GB, and hence the whole
-     * structure must satisfy this restriction. Thus we specify MEMF_bits(32).
-     */
-    unsigned int memflags =
-        (is_hvm_domain(d) && paging_mode_shadow(d)) ? MEMF_bits(32) : 0;
-
-    BUILD_BUG_ON(sizeof(*v) > PAGE_SIZE);
-    v = alloc_xenheap_pages(0, memflags);
-    if ( v != NULL )
-        clear_page(v);
-    return v;
-}
-
-void free_vcpu_struct(struct vcpu *v)
-{
-    free_xenheap_page(v);
-}
-
 /* Initialise various registers to their architectural INIT/RESET state. */
 void arch_vcpu_regs_init(struct vcpu *v)
 {
diff --git a/xen/arch/x86/include/asm/domain.h 
b/xen/arch/x86/include/asm/domain.h
index 16cd45cc32c0..effb23a23416 100644
--- a/xen/arch/x86/include/asm/domain.h
+++ b/xen/arch/x86/include/asm/domain.h
@@ -15,6 +15,18 @@
 unsigned int arch_domain_struct_memflags(void);
 #define arch_domain_struct_memflags arch_domain_struct_memflags
 
+/*
+ * This structure contains embedded PAE PDPTEs, used when an HVM guest
+ * runs on shadow pagetables outside of 64-bit mode. In this case the CPU
+ * may require that the shadow CR3 points below 4GB, and hence the whole
+ * structure must satisfy this restriction. Thus we specify MEMF_bits(32).
+ */
+#define arch_vcpu_struct_memflags(d) ({                                 \
+    const struct domain *d_ = (d);                                      \
+                                                                        \
+    (is_hvm_domain(d_) && paging_mode_shadow(d_) ? MEMF_bits(32) : 0);  \
+})
+
 #define has_32bit_shinfo(d)    ((d)->arch.has_32bit_shinfo)
 
 /*
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 93c71bc766b0..655d9590f846 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -316,6 +316,26 @@ static void vcpu_info_reset(struct vcpu *v)
          : &dummy_vcpu_info);
 }
 
+static struct vcpu *alloc_vcpu_struct(const struct domain *d)
+{
+#ifndef arch_vcpu_struct_memflags
+# define arch_vcpu_struct_memflags(d) ((void)(d), 0)
+#endif
+    struct vcpu *v;
+
+    BUILD_BUG_ON(sizeof(*v) > PAGE_SIZE);
+    v = alloc_xenheap_pages(0, arch_vcpu_struct_memflags(d));
+    if ( v )
+        clear_page(v);
+
+    return v;
+}
+
+static void free_vcpu_struct(struct vcpu *v)
+{
+    free_xenheap_page(v);
+}
+
 static void vmtrace_free_buffer(struct vcpu *v)
 {
     const struct domain *d = v->domain;
diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h
index 8aab05ae93c8..644f5ac3f293 100644
--- a/xen/include/xen/domain.h
+++ b/xen/include/xen/domain.h
@@ -70,10 +70,6 @@ void domid_free(domid_t domid);
 struct domain *alloc_domain_struct(void);
 void free_domain_struct(struct domain *d);
 
-/* Allocate/free a VCPU structure. */
-struct vcpu *alloc_vcpu_struct(const struct domain *d);
-void free_vcpu_struct(struct vcpu *v);
-
 /* Allocate/free a PIRQ structure. */
 #ifndef alloc_pirq_struct
 struct pirq *alloc_pirq_struct(struct domain *d);
-- 
2.52.0




 


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