[xen staging] x86+libxl: correct p2m (shadow) memory pool size calculation

[patchbot@xxxxxxx]

commit 2c992810854a15b41be920519ce83a4a328d5168
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Apr 28 10:00:49 2022 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Apr 28 10:00:49 2022 +0200

    x86+libxl: correct p2m (shadow) memory pool size calculation
    
    The reference "to shadow the resident processes" is applicable to
    domains (potentially) running in shadow mode only. Adjust the
    calculations accordingly. This, however, requires further parameters.
    Since the original function is deprecated anyway, and since it can't be
    changed (for being part of a stable ABI), introduce a new (internal
    only) function, with the deprecated one simply becoming a wrapper.
    
    In dom0_paging_pages() also take the opportunity and stop open-coding
    DIV_ROUND_UP().
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/libs/light/libxl_create.c   | 30 +++++++++++++++++++++++++++---
 tools/libs/light/libxl_internal.h |  5 +++++
 tools/libs/light/libxl_utils.c    |  9 ++-------
 xen/arch/x86/dom0_build.c         |  9 ++++++---
 4 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/tools/libs/light/libxl_create.c b/tools/libs/light/libxl_create.c
index 885675591f..69ec405858 100644
--- a/tools/libs/light/libxl_create.c
+++ b/tools/libs/light/libxl_create.c
@@ -1027,6 +1027,24 @@ static bool ok_to_default_memkb_in_create(libxl__gc *gc)
      */
 }
 
+unsigned long libxl__get_required_paging_memory(unsigned long maxmem_kb,
+                                                unsigned int smp_cpus,
+                                                libxl_domain_type type,
+                                                bool hap)
+{
+    /*
+     * 256 pages (1MB) per vcpu,
+     * plus 1 page per MiB of RAM for the P2M map (for non-PV guests),
+     * plus 1 page per MiB of RAM to shadow the resident processes (for shadow
+     * mode guests).
+     * This is higher than the minimum that Xen would allocate if no value
+     * were given (but the Xen minimum is for safety, not performance).
+     */
+    return 4 * (256 * smp_cpus +
+                ((type != LIBXL_DOMAIN_TYPE_PV) + !hap) *
+                (maxmem_kb / 1024));
+}
+
 static unsigned long libxl__get_required_iommu_memory(unsigned long maxmem_kb)
 {
     unsigned long iommu_pages = 0, mem_pages = maxmem_kb / 4;
@@ -1194,10 +1212,16 @@ int libxl__domain_config_setdefault(libxl__gc *gc,
     }
 
     if (d_config->b_info.shadow_memkb == LIBXL_MEMKB_DEFAULT
-        && ok_to_default_memkb_in_create(gc))
+        && ok_to_default_memkb_in_create(gc)) {
+        bool hap = d_config->c_info.type != LIBXL_DOMAIN_TYPE_PV &&
+                   libxl_defbool_val(d_config->c_info.hap);
+
         d_config->b_info.shadow_memkb =
-            libxl_get_required_shadow_memory(d_config->b_info.max_memkb,
-                                             d_config->b_info.max_vcpus);
+            libxl__get_required_paging_memory(d_config->b_info.max_memkb,
+                                              d_config->b_info.max_vcpus,
+                                              d_config->c_info.type,
+                                              hap);
+    }
 
     /* No IOMMU reservation is needed if passthrough mode is not 'sync_pt' */
     if (d_config->b_info.iommu_memkb == LIBXL_MEMKB_DEFAULT
diff --git a/tools/libs/light/libxl_internal.h 
b/tools/libs/light/libxl_internal.h
index a26daec040..bdef5a605e 100644
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -1569,6 +1569,11 @@ _hidden int 
libxl__domain_need_memory_calculate(libxl__gc *gc,
                                       libxl_domain_build_info *b_info,
                                       uint64_t *need_memkb);
 
+_hidden unsigned long libxl__get_required_paging_memory(unsigned long 
maxmem_kb,
+                                                        unsigned int smp_cpus,
+                                                        libxl_domain_type type,
+                                                        bool hap);
+
 _hidden const char *libxl__device_nic_devname(libxl__gc *gc,
                                               uint32_t domid,
                                               uint32_t devid,
diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c
index b91c2cafa2..1d8a7f64ef 100644
--- a/tools/libs/light/libxl_utils.c
+++ b/tools/libs/light/libxl_utils.c
@@ -38,13 +38,8 @@ char *libxl_basename(const char *name)
 
 unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, 
unsigned int smp_cpus)
 {
-    /* 256 pages (1MB) per vcpu,
-       plus 1 page per MiB of RAM for the P2M map,
-       plus 1 page per MiB of RAM to shadow the resident processes.
-       This is higher than the minimum that Xen would allocate if no value
-       were given (but the Xen minimum is for safety, not performance).
-     */
-    return 4 * (256 * smp_cpus + 2 * (maxmem_kb / 1024));
+    return libxl__get_required_paging_memory(maxmem_kb, smp_cpus,
+                                             LIBXL_DOMAIN_TYPE_INVALID, false);
 }
 
 char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid)
diff --git a/xen/arch/x86/dom0_build.c b/xen/arch/x86/dom0_build.c
index 4d1c5c60e4..79234f18ff 100644
--- a/xen/arch/x86/dom0_build.c
+++ b/xen/arch/x86/dom0_build.c
@@ -314,12 +314,15 @@ unsigned int __initdata dom0_memflags = 
MEMF_no_dma|MEMF_exact_node;
 unsigned long __init dom0_paging_pages(const struct domain *d,
                                        unsigned long nr_pages)
 {
-    /* Copied from: libxl_get_required_shadow_memory() */
+    /* Keep in sync with libxl__get_required_paging_memory(). */
     unsigned long memkb = nr_pages * (PAGE_SIZE / 1024);
 
-    memkb = 4 * (256 * d->max_vcpus + 2 * (memkb / 1024));
+    memkb = 4 * (256 * d->max_vcpus +
+                 (is_pv_domain(d) ? opt_dom0_shadow || opt_pv_l1tf_hwdom
+                                  : 1 + opt_dom0_shadow) *
+                 (memkb / 1024));
 
-    return ((memkb + 1023) / 1024) << (20 - PAGE_SHIFT);
+    return DIV_ROUND_UP(memkb, 1024) << (20 - PAGE_SHIFT);
 }
 
 
--
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