[v6,4/7] xen/pvh: Move Xen specific PVH VM initialization out of common file

Commit Message

Maran Wilson April 4, 2018, 8:32 p.m. UTC

We need to refactor PVH entry code so that support for other hypervisors
like Qemu/KVM can be added more easily.

This patch moves the small block of code used for initializing Xen PVH
virtual machines into the Xen specific file. This initialization is not
going to be needed for Qemu/KVM guests. Moving it out of the common file
is going to allow us to compile kernels in the future without CONFIG_XEN
that are still capable of being booted as a Qemu/KVM guest via the PVH
entry point.

Signed-off-by: Maran Wilson <[e-mail]>
Reviewed-by: Konrad Rzeszutek Wilk <[e-mail]>
Reviewed-by: Juergen Gross <[e-mail]>
---
 arch/x86/platform/pvh/enlighten.c | 28 ++++++++++++++++++++--------
 arch/x86/xen/enlighten_pvh.c      | 18 +++++++++++++++++-
 2 files changed, 37 insertions(+), 9 deletions(-)

Comments

kernel test robot April 5, 2018, 9:59 a.m. UTC | #1

Hi Maran,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on next-20180404]
[cannot apply to tip/x86/core xen-tip/linux-next v4.16]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Maran-Wilson/KVM-x86-Allow-Qemu-KVM-to-use-PVH-entry-point/20180405-165048
config: i386-randconfig-x019-201813 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   arch/x86/xen/enlighten_pvh.c: In function 'xen_pvh_init':
>> arch/x86/xen/enlighten_pvh.c:23:18: error: implicit declaration of function 'xen_cpuid_base'; did you mean 'get_pid_task'? [-Werror=implicit-function-declaration]
     msr = cpuid_ebx(xen_cpuid_base() + 2);
                     ^~~~~~~~~~~~~~
                     get_pid_task
   cc1: some warnings being treated as errors

vim +23 arch/x86/xen/enlighten_pvh.c

    15	
    16	void __init xen_pvh_init(void)
    17	{
    18		u32 msr;
    19		u64 pfn;
    20	
    21		xen_pvh = 1;
    22	
  > 23		msr = cpuid_ebx(xen_cpuid_base() + 2);

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Patch

diff --git a/arch/x86/platform/pvh/enlighten.c b/arch/x86/platform/pvh/enlighten.c
index 74ff1c3d2789..edcff7de0529 100644
--- a/arch/x86/platform/pvh/enlighten.c
+++ b/arch/x86/platform/pvh/enlighten.c
@@ -80,26 +80,38 @@  static void __init init_pvh_bootparams(void)
 	x86_init.acpi.get_root_pointer = pvh_get_root_pointer;
 }
 
+/*
+ * If we are trying to boot a Xen PVH guest, it is expected that the kernel
+ * will have been configured to provide the required override for this routine.
+ */
+void __init __weak xen_pvh_init(void)
+{
+	xen_raw_printk("Error: Missing xen PVH initialization\n");
+	BUG();
+}
+
+/*
+ * When we add support for other hypervisors like Qemu/KVM, this routine can
+ * selectively invoke the appropriate initialization based on guest type.
+ */
+static void hypervisor_specific_init(void)
+{
+	xen_pvh_init();
+}
+
 /*
  * This routine (and those that it might call) should not use
  * anything that lives in .bss since that segment will be cleared later.
  */
 void __init xen_prepare_pvh(void)
 {
-	u32 msr;
-	u64 pfn;
-
 	if (pvh_start_info.magic != XEN_HVM_START_MAGIC_VALUE) {
 		xen_raw_printk("Error: Unexpected magic value (0x%08x)\n",
 				pvh_start_info.magic);
 		BUG();
 	}
 
-	xen_pvh = 1;
-
-	msr = cpuid_ebx(xen_cpuid_base() + 2);
-	pfn = __pa(hypercall_page);
-	wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32));
+	hypervisor_specific_init();
 
 	init_pvh_bootparams();
 }
diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
index c5409c1f259f..08fc63d14ae5 100644
--- a/arch/x86/xen/enlighten_pvh.c
+++ b/arch/x86/xen/enlighten_pvh.c
@@ -1,4 +1,9 @@ 
-#include <linux/types.h>
+#include <linux/acpi.h>
+
+#include <asm/io_apic.h>
+
+#include <asm/xen/interface.h>
+#include <asm/xen/hypercall.h>
 
 /*
  * PVH variables.
@@ -8,3 +13,14 @@ 
  */
 bool xen_pvh __attribute__((section(".data"))) = 0;
 
+void __init xen_pvh_init(void)
+{
+	u32 msr;
+	u64 pfn;
+
+	xen_pvh = 1;
+
+	msr = cpuid_ebx(xen_cpuid_base() + 2);
+	pfn = __pa(hypercall_page);
+	wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32));
+}