[PATCH for-4.15] x86/mem_sharing: copy parent VM's hostp2m's max_mapped_pfn during forking

From: Tamas K Lengyel <tamas.lengyel@intel.com>
To: xen-devel@lists.xenproject.org
Cc: "Tamas K Lengyel" <tamas.lengyel@intel.com>,
	"Tamas K Lengyel" <tamas@tklengyel.com>,
	"Jan Beulich" <jbeulich@suse.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"George Dunlap" <george.dunlap@citrix.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>
Subject: [PATCH for-4.15] x86/mem_sharing: copy parent VM's hostp2m's max_mapped_pfn during forking
Date: Thu, 18 Mar 2021 14:36:32 -0700	[thread overview]
Message-ID: <bdeaf7893acd6497cc2b88f3a1357d1299960e9b.1616103095.git.tamas.lengyel@intel.com> (raw)

When creating a VM fork copy the parent VM's hostp2m max_mapped_pfn value. Some
toolstack relies on the XENMEM_maximum_gpfn value to establish the maximum
addressable physical memory in the VM and for forks that have not yet been
unpaused that value is not going to reflect the correct max gpfn that's
possible to populate into the p2m. This patch fixes the issue.

Signed-off-by: Tamas K Lengyel <tamas.lengyel@intel.com>
---
 xen/arch/x86/mm/mem_sharing.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 00ada05c10..98b14f7b0a 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -1761,6 +1761,7 @@ static int copy_settings(struct domain *cd, struct domain *d)
         return rc;
 
     copy_tsc(cd, d);
+    p2m_get_hostp2m(cd)->max_mapped_pfn = p2m_get_hostp2m(d)->max_mapped_pfn;
 
     return rc;
 }
-- 
2.25.1


