From 8b25551baa3307af0aa1ef8f7f43403f01c2c5d7 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 5 Sep 2019 09:56:42 +0200 Subject: [PATCH] x86/shadow: don't enable shadow mode with too small a shadow allocation (part 2) Commit 2634b997af ("x86/shadow: don't enable shadow mode with too small a shadow allocation") was incomplete: The adjustment done there to shadow_enable() is also needed in shadow_one_bit_enable(). The (new) problem report was (apparently) a failed PV guest migration followed by another migration attempt for that same guest. Disabling log-dirty mode after the first one had left a couple of shadow pages allocated (perhaps something that also wants fixing), and hence the second enabling of log-dirty mode wouldn't have allocated anything further. Reported-by: James Wang Signed-off-by: Jan Beulich Acked-by: Tim Deegan --- xen/arch/x86/mm/shadow/common.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c index 9463794059..bc9d41d38b 100644 --- a/xen/arch/x86/mm/shadow/common.c +++ b/xen/arch/x86/mm/shadow/common.c @@ -2864,7 +2864,8 @@ static int shadow_one_bit_enable(struct domain *d, u32 mode) mode |= PG_SH_enable; - if ( d->arch.paging.shadow.total_pages == 0 ) + if ( d->arch.paging.shadow.total_pages < + sh_min_allocation(d) + d->arch.paging.shadow.p2m_pages ) { /* Init the shadow memory allocation if the user hasn't done so */ if ( shadow_set_allocation(d, 1, NULL) != 0 ) -- 2.30.2