xen: introduce Kconfig ARCH_PAGING_MEMPOOL

ARM MPU system doesn't need to use paging memory pool, as MPU memory
mapping table at most takes only one 4KB page, which is enough to
manage the maximum 255 MPU memory regions, for all EL2 stage 1
translation and EL1 stage 2 translation.

Introduce ARCH_PAGING_MEMPOOL Kconfig common symbol, selected for Arm
MMU systems and x86. Removed stubs from RISC-V now that the common code
provide them and the functions are not gonna be used.

Wrap the code inside 'construct_domU' that deal with p2m paging
allocation in a new function 'domain_p2m_set_allocation', protected
by ARCH_PAGING_MEMPOOL, this is done in this way to prevent polluting
the former function with #ifdefs and improve readability

Introduce arch_{get,set}_paging_mempool_size stubs for architecture
with !ARCH_PAGING_MEMPOOL.

Remove 'struct paging_domain' from Arm 'struct arch_domain' when the
field is not required.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Signed-off-by: Wei Chen <wei.chen@arm.com>
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com> # arm
Reviewed-by: Oleksii Kurochko <oleksii.kurochko@gmail.com> # riscv
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/arm/Kconfig

@@ -75,6 +75,7 @@ choice
 
 config MMU
 	bool "MMU"
+	select ARCH_PAGING_MEMPOOL
 	select HAS_LLC_COLORING if !NUMA && ARM_64
 	select HAS_PMAP
 	select HAS_VMAP

xen/arch/arm/dom0less-build.c

@@ -673,21 +673,6 @@ static int __init prepare_dtb_domU(struct domain *d, struct kernel_info *kinfo)
     return -EINVAL;
 }
 
-static unsigned long __init domain_p2m_pages(unsigned long maxmem_kb,
-                                             unsigned int smp_cpus)
-{
-    /*
-     * Keep in sync with libxl__get_required_paging_memory().
-     * 256 pages (1MB) per vcpu, plus 1 page per MiB of RAM for the P2M map,
-     * plus 128 pages to cover extended regions.
-     */
-    unsigned long memkb = 4 * (256 * smp_cpus + (maxmem_kb / 1024) + 128);
-
-    BUILD_BUG_ON(PAGE_SIZE != SZ_4K);
-
-    return DIV_ROUND_UP(memkb, 1024) << (20 - PAGE_SHIFT);
-}
-
 static int __init alloc_xenstore_evtchn(struct domain *d)
 {
     evtchn_alloc_unbound_t alloc;
@@ -841,23 +826,28 @@ static void __init domain_vcpu_affinity(struct domain *d,
     }
 }
 
-static int __init construct_domU(struct domain *d,
-                                 const struct dt_device_node *node)
+#ifdef CONFIG_ARCH_PAGING_MEMPOOL
+static unsigned long __init domain_p2m_pages(unsigned long maxmem_kb,
+                                             unsigned int smp_cpus)
 {
-    struct kernel_info kinfo = KERNEL_INFO_INIT;
-    const char *dom0less_enhanced;
-    int rc;
-    u64 mem;
-    u32 p2m_mem_mb;
-    unsigned long p2m_pages;
+    /*
+     * Keep in sync with libxl__get_required_paging_memory().
+     * 256 pages (1MB) per vcpu, plus 1 page per MiB of RAM for the P2M map,
+     * plus 128 pages to cover extended regions.
+     */
+    unsigned long memkb = 4 * (256 * smp_cpus + (maxmem_kb / 1024) + 128);
 
-    rc = dt_property_read_u64(node, "memory", &mem);
-    if ( !rc )
-    {
-        printk("Error building DomU: cannot read \"memory\" property\n");
-        return -EINVAL;
-    }
-    kinfo.unassigned_mem = (paddr_t)mem * SZ_1K;
+    BUILD_BUG_ON(PAGE_SIZE != SZ_4K);
+
+    return DIV_ROUND_UP(memkb, 1024) << (20 - PAGE_SHIFT);
+}
+
+static int __init domain_p2m_set_allocation(struct domain *d, uint64_t mem,
+                                            const struct dt_device_node *node)
+{
+    unsigned long p2m_pages;
+    uint32_t p2m_mem_mb;
+    int rc;
 
     rc = dt_property_read_u32(node, "xen,domain-p2m-mem-mb", &p2m_mem_mb);
     /* If xen,domain-p2m-mem-mb is not specified, use the default value. */
@@ -868,6 +858,34 @@ static int __init construct_domU(struct domain *d,
     spin_lock(&d->arch.paging.lock);
     rc = p2m_set_allocation(d, p2m_pages, NULL);
     spin_unlock(&d->arch.paging.lock);
+
+    return rc;
+}
+#else /* !CONFIG_ARCH_PAGING_MEMPOOL */
+static inline int domain_p2m_set_allocation(struct domain *d, uint64_t mem,
+                                            const struct dt_device_node *node)
+{
+    return 0;
+}
+#endif /* CONFIG_ARCH_PAGING_MEMPOOL */
+
+static int __init construct_domU(struct domain *d,
+                                 const struct dt_device_node *node)
+{
+    struct kernel_info kinfo = KERNEL_INFO_INIT;
+    const char *dom0less_enhanced;
+    int rc;
+    u64 mem;
+
+    rc = dt_property_read_u64(node, "memory", &mem);
+    if ( !rc )
+    {
+        printk("Error building DomU: cannot read \"memory\" property\n");
+        return -EINVAL;
+    }
+    kinfo.unassigned_mem = (paddr_t)mem * SZ_1K;
+
+    rc = domain_p2m_set_allocation(d, mem, node);
     if ( rc != 0 )
         return rc;
 

xen/arch/arm/include/asm/domain.h

@@ -75,7 +75,9 @@ struct arch_domain
 
     struct hvm_domain hvm;
 
+#ifdef CONFIG_ARCH_PAGING_MEMPOOL
     struct paging_domain paging;
+#endif
 
     struct vmmio vmmio;
 

xen/arch/riscv/stubs.c

@@ -333,11 +333,6 @@ void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
 
 /* p2m.c */
 
-int arch_set_paging_mempool_size(struct domain *d, uint64_t size)
-{
-    BUG_ON("unimplemented");
-}
-
 int unmap_mmio_regions(struct domain *d,
                        gfn_t start_gfn,
                        unsigned long nr,
@@ -360,12 +355,6 @@ int set_foreign_p2m_entry(struct domain *d, const struct domain *fd,
     BUG_ON("unimplemented");
 }
 
-/* Return the size of the pool, in bytes. */
-int arch_get_paging_mempool_size(struct domain *d, uint64_t *size)
-{
-    BUG_ON("unimplemented");
-}
-
 int guest_physmap_remove_page(struct domain *d, gfn_t gfn, mfn_t mfn,
                               unsigned int page_order)
 {

xen/arch/x86/Kconfig

@@ -9,6 +9,7 @@ config X86
 	select ACPI_NUMA
 	select ALTERNATIVE_CALL
 	select ARCH_MAP_DOMAIN_PAGE
+	select ARCH_PAGING_MEMPOOL
 	select ARCH_SUPPORTS_INT128
 	imply CORE_PARKING
 	select FUNCTION_ALIGNMENT_16B

xen/common/Kconfig

@@ -44,6 +44,9 @@ config ALTERNATIVE_CALL
 config ARCH_MAP_DOMAIN_PAGE
 	bool
 
+config ARCH_PAGING_MEMPOOL
+	bool
+
 config GENERIC_BUG_FRAME
 	bool
 

xen/include/xen/domain.h

@@ -2,6 +2,7 @@
 #ifndef __XEN_DOMAIN_H__
 #define __XEN_DOMAIN_H__
 
+#include <xen/errno.h>
 #include <xen/numa.h>
 #include <xen/types.h>
 
@@ -114,9 +115,25 @@ void arch_get_info_guest(struct vcpu *v, vcpu_guest_context_u c);
 int arch_initialise_vcpu(struct vcpu *v, XEN_GUEST_HANDLE_PARAM(void) arg);
 int default_initialise_vcpu(struct vcpu *v, XEN_GUEST_HANDLE_PARAM(void) arg);
 
+#ifdef CONFIG_ARCH_PAGING_MEMPOOL
+
 int arch_get_paging_mempool_size(struct domain *d, uint64_t *size /* bytes */);
 int arch_set_paging_mempool_size(struct domain *d, uint64_t size /* bytes */);
 
+#else /* !CONFIG_ARCH_PAGING_MEMPOOL */
+
+static inline int arch_get_paging_mempool_size(struct domain *d, uint64_t *size)
+{
+    return -EOPNOTSUPP;
+}
+
+static inline int arch_set_paging_mempool_size(struct domain *d, uint64_t size)
+{
+    return -EOPNOTSUPP;
+}
+
+#endif /* CONFIG_ARCH_PAGING_MEMPOOL */
+
 bool update_runstate_area(struct vcpu *v);
 
 int domain_relinquish_resources(struct domain *d);