File 5adde9ed-xpti-fix-double-fault-handling.patch of Package xen.8389
From: Juergen Gross <jgross@suse.com>
Subject: xpti: fix bug in double fault handling
When entering the hypervisor via the double fault handler resetting
xen_cr3 was missing. This led to switching to pv_cr3 when returning
from the next following exception, so repair this in order to allow
exception handling to work even after a double fault.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
xen/arch/x86/x86_64/entry.S | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 45d9842d09..1cd7d93892 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -783,12 +783,14 @@ ENTRY(double_fault)
/* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */
mov STACK_CPUINFO_FIELD(xen_cr3)(%r14), %rbx
- test %rbx, %rbx
+ neg %rbx
jz .Ldblf_cr3_okay
jns .Ldblf_cr3_load
+ mov %rbx, STACK_CPUINFO_FIELD(xen_cr3)(%r14)
neg %rbx
.Ldblf_cr3_load:
mov %rbx, %cr3
+ movq $0, STACK_CPUINFO_FIELD(xen_cr3)(%r14)
.Ldblf_cr3_okay:
movq %rsp,%rdi
--
2.11.0