[PATCH 0/2] libxl: fix soft reset for PVHv2 guests

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Hi,

I'm trying to make kexec/kdump work for PVHv2 guests too. PVHv2 guests are
almost HVM guests so no major changes to the soft reset procedures are
required. A few issues, however, arose during testing.

Linux also requires some changes to boot after kexec. As PVH guests boot
like normal HVM guests after kexec we need to detect their 'PVH-ness'
somehow here's a hack which utilizes XEN_IOPORT_MAGIC:

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index ec1d5c4..b9f3fdf 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -51,6 +51,7 @@
 #include <xen/hvm.h>
 #include <xen/hvc-console.h>
 #include <xen/acpi.h>
+#include <xen/platform_pci.h>
 
 #include <asm/paravirt.h>
 #include <asm/apic.h>
@@ -1765,6 +1766,19 @@ void __init xen_prepare_pvh(void)
 
        x86_init.oem.arch_setup = xen_pvh_arch_setup;
 }
+
+static void xen_detect_pvh(void) {
+       short magic;
+
+       if (xen_pvh)
+               return;
+
+       magic = inw(XEN_IOPORT_MAGIC);
+       if (magic != XEN_IOPORT_MAGIC_VAL) {
+               xen_pvh = 1;
+               xen_pvh_arch_setup();
+       }
+}
 #endif
 
 void __ref xen_hvm_init_shared_info(void)
@@ -1912,6 +1926,9 @@ static void __init xen_hvm_guest_init(void)
 
        init_hvm_pv_info();
 
+       /* Detect PVH booting after kexec */
+       xen_detect_pvh();
+
        xen_hvm_init_shared_info();
 
        xen_panic_handler_init();

With the hack I was able to do kdump on a PVHv2 guest. I'll start a separate
mail thread to discuss how we should do it right.

Vitaly Kuznetsov (2):
  libxl: don't try to rename dm save file for PVH
  libxl: preserve console tty across soft reset

 tools/libxl/libxl_console.c  |  5 ++++-
 tools/libxl/libxl_create.c   | 24 +++++++++++++++++-------
 tools/libxl/libxl_internal.h |  1 +
 3 files changed, 22 insertions(+), 8 deletions(-)

-- 
2.9.3


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