[Xen-devel] [RFC Patch v4 7/8] x86/hvm: bump the number of pages of shadow memory

[Chao Gao <chao.gao@xxxxxxxxx>]

Each vcpu of hvm guest consumes at least one shadow page. Currently, only 256
(for hap case) pages are pre-allocated as shadow memory at beginning. It would
run out if guest has more than 256 vcpus and guest creation fails. Bump the
number of shadow pages to 2 * HVM_MAX_VCPUS for hap case and 8 * HVM_MAX_VCPUS
for shadow case.

This patch won't lead to more memory consumption for the size of shadow memory
will be adjusted via XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION according to the size
of guest memory and the number of vcpus.

Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
---
 xen/arch/x86/mm/hap/hap.c       | 2 +-
 xen/arch/x86/mm/shadow/common.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index 41deb90..f4cf578 100644
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -455,7 +455,7 @@ int hap_enable(struct domain *d, u32 mode)
     if ( old_pages == 0 )
     {
         paging_lock(d);
-        rv = hap_set_allocation(d, 256, NULL);
+        rv = hap_set_allocation(d, 2 * HVM_MAX_VCPUS, NULL);
         if ( rv != 0 )
         {
             hap_set_allocation(d, 0, NULL);
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 72c674e..5e66603 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -3093,7 +3093,7 @@ int shadow_enable(struct domain *d, u32 mode)
     if ( old_pages == 0 )
     {
         paging_lock(d);
-        rv = shadow_set_allocation(d, 1024, NULL); /* Use at least 4MB */
+        rv = shadow_set_allocation(d, 8 * HVM_MAX_VCPUS, NULL);
         if ( rv != 0 )
         {
             shadow_set_allocation(d, 0, NULL);
-- 
1.8.3.1


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