[xen staging] x86/PV: properly set shadow allocation for Dom0

[patchbot@xxxxxxx]

commit c037dfb909406de6febaaa2c2e05743186e1e07e
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Dec 3 11:14:24 2021 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Dec 3 11:14:24 2021 +0100

    x86/PV: properly set shadow allocation for Dom0
    
    Leaving shadow setup just to the L1TF tasklet means running Dom0 on a
    minimally acceptable shadow memory pool, rather than what normally
    would be used (also, for example, for PVH). Populate the pool before
    triggering the tasklet (or in preparation for L1TF checking logic to
    trigger it), on a best effort basis (again like done for PVH).
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Tim Deegan <tim@xxxxxxx>
---
 xen/arch/x86/mm/shadow/common.c |  2 +-
 xen/arch/x86/pv/dom0_build.c    | 17 ++++++++++++++++-
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index de09ef5cae..6221630fc2 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1298,7 +1298,7 @@ int shadow_set_allocation(struct domain *d, unsigned int 
pages, bool *preempted)
 {
     struct page_info *sp;
 
-    ASSERT(paging_locked_by_me(d));
+    ASSERT(paging_locked_by_me(d) || system_state < SYS_STATE_active);
 
     if ( pages > 0 )
     {
diff --git a/xen/arch/x86/pv/dom0_build.c b/xen/arch/x86/pv/dom0_build.c
index cb68da75c1..e501979a86 100644
--- a/xen/arch/x86/pv/dom0_build.c
+++ b/xen/arch/x86/pv/dom0_build.c
@@ -21,6 +21,7 @@
 #include <asm/page.h>
 #include <asm/pv/mm.h>
 #include <asm/setup.h>
+#include <asm/shadow.h>
 
 /* Allow ring-3 access in long mode as guest cannot use ring 1 ... */
 #define BASE_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_USER)
@@ -928,8 +929,22 @@ int __init dom0_construct_pv(struct domain *d,
     if ( d->domain_id == hardware_domid )
         iommu_hwdom_init(d);
 
-    /* Activate shadow mode, if requested.  Reuse the pv_l1tf tasklet. */
 #ifdef CONFIG_SHADOW_PAGING
+    /* Fill the shadow pool if necessary. */
+    if ( opt_dom0_shadow || opt_pv_l1tf_hwdom )
+    {
+        bool preempted;
+
+        nr_pt_pages = dom0_paging_pages(d, nr_pages);
+
+        do {
+            preempted = false;
+            shadow_set_allocation(d, nr_pt_pages, &preempted);
+            process_pending_softirqs();
+        } while ( preempted );
+    }
+
+    /* Activate shadow mode, if requested.  Reuse the pv_l1tf tasklet. */
     if ( opt_dom0_shadow )
     {
         printk("Switching dom0 to using shadow paging\n");
--
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