From 83ac5ab54bba37e2761d77584ab9e2d8a24401c9 Mon Sep 17 00:00:00 2001 From: Sergey Dyasli Date: Wed, 30 Oct 2019 14:54:47 +0000 Subject: [PATCH] x86/e820: fix 640k - 1M region reservation logic Converting a guest from PV to PV-in-PVH makes the guest to have 384k less memory, which may confuse guest's balloon driver. This happens because Xen unconditionally reserves 640k - 1M region in E820 despite the fact that it's really a usable RAM in PVH boot mode. Fix this by skipping region type change in virtualised environments, trusting whatever memory map our hypervisor has provided. Signed-off-by: Sergey Dyasli Reviewed-by: Andrew Cooper Reviewed-by: Jan Beulich Release-acked-by: Juergen Gross --- xen/arch/x86/e820.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/e820.c b/xen/arch/x86/e820.c index 8e8a2c4e1b..082f9928a1 100644 --- a/xen/arch/x86/e820.c +++ b/xen/arch/x86/e820.c @@ -318,9 +318,9 @@ static int __init copy_e820_map(struct e820entry * biosmap, unsigned int nr_map) /* * Some BIOSes claim RAM in the 640k - 1M region. - * Not right. Fix it up. + * Not right. Fix it up, but only when running on bare metal. */ - if (type == E820_RAM) { + if (!cpu_has_hypervisor && type == E820_RAM) { if (start < 0x100000ULL && end > 0xA0000ULL) { if (start < 0xA0000ULL) add_memory_region(start, 0xA0000ULL-start, type); -- 2.39.5