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[xen staging] xen: introduce Kconfig ARCH_PAGING_MEMPOOL



commit 2705f1adb9df93ee632a52651cf2b6bb86d9ca35
Author:     Penny Zheng <Penny.Zheng@xxxxxxx>
AuthorDate: Tue Apr 1 09:58:57 2025 +0100
Commit:     Michal Orzel <michal.orzel@xxxxxxx>
CommitDate: Wed Apr 2 11:15:10 2025 +0200

    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@xxxxxxx>
    Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
    Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
    Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx> # arm
    Reviewed-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx> # riscv
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/arm/Kconfig              |  1 +
 xen/arch/arm/dom0less-build.c     | 70 ++++++++++++++++++++++++---------------
 xen/arch/arm/include/asm/domain.h |  2 ++
 xen/arch/riscv/stubs.c            | 11 ------
 xen/arch/x86/Kconfig              |  1 +
 xen/common/Kconfig                |  3 ++
 xen/include/xen/domain.h          | 17 ++++++++++
 7 files changed, 68 insertions(+), 37 deletions(-)

diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index 7a7658812d..565f288331 100644
--- a/xen/arch/arm/Kconfig
+++ b/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
diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
index 573b0d25ae..bd15563750 100644
--- a/xen/arch/arm/dom0less-build.c
+++ b/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;
@@ -841,6 +826,49 @@ static void __init domain_vcpu_affinity(struct domain *d,
     }
 }
 
+#ifdef CONFIG_ARCH_PAGING_MEMPOOL
+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 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. */
+    p2m_pages = rc ?
+                p2m_mem_mb << (20 - PAGE_SHIFT) :
+                domain_p2m_pages(mem, d->max_vcpus);
+
+    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)
 {
@@ -848,8 +876,6 @@ static int __init construct_domU(struct domain *d,
     const char *dom0less_enhanced;
     int rc;
     u64 mem;
-    u32 p2m_mem_mb;
-    unsigned long p2m_pages;
 
     rc = dt_property_read_u64(node, "memory", &mem);
     if ( !rc )
@@ -859,15 +885,7 @@ static int __init construct_domU(struct domain *d,
     }
     kinfo.unassigned_mem = (paddr_t)mem * SZ_1K;
 
-    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. */
-    p2m_pages = rc ?
-                p2m_mem_mb << (20 - PAGE_SHIFT) :
-                domain_p2m_pages(mem, d->max_vcpus);
-
-    spin_lock(&d->arch.paging.lock);
-    rc = p2m_set_allocation(d, p2m_pages, NULL);
-    spin_unlock(&d->arch.paging.lock);
+    rc = domain_p2m_set_allocation(d, mem, node);
     if ( rc != 0 )
         return rc;
 
diff --git a/xen/arch/arm/include/asm/domain.h 
b/xen/arch/arm/include/asm/domain.h
index 50b6a4b009..a3487ca713 100644
--- a/xen/arch/arm/include/asm/domain.h
+++ b/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;
 
diff --git a/xen/arch/riscv/stubs.c b/xen/arch/riscv/stubs.c
index caa133de84..a1d64534cd 100644
--- a/xen/arch/riscv/stubs.c
+++ b/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)
 {
diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index 18efdb2e31..de2fa37f08 100644
--- a/xen/arch/x86/Kconfig
+++ b/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
diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index a6aa2c5c14..218357d593 100644
--- a/xen/common/Kconfig
+++ b/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
 
diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h
index 83069de501..a34daa7d10 100644
--- a/xen/include/xen/domain.h
+++ b/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);
--
generated by git-patchbot for /home/xen/git/xen.git#staging



 


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