linux-kernel - [PATCH v3] xen: share start flags between PV and PVH

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Date:   Fri, 8 Jun 2018 10:40:38 +0200
From:   Roger Pau Monne <roger.pau@...rix.com>
To:     <linux-kernel@...r.kernel.org>
CC:     Roger Pau Monne <roger.pau@...rix.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        <xen-devel@...ts.xenproject.org>
Subject: [PATCH v3] xen: share start flags between PV and PVH

Use a global variable to store the start flags for both PV and PVH.
This allows the xen_initial_domain macro to work properly on PVH.

Note that ARM is also switched to use the new variable.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Roger Pau Monné <roger.pau@...rix.com>
---
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Stefano Stabellini <sstabellini@...nel.org>
Cc: xen-devel@...ts.xenproject.org
---
Changes since v2:
 - Declare xen_start_flags outside of the XEN_DOM0 guard and include
   types.h.

Changes since v1:
 - Switch ARM to also use the new xen_start_flags.
---
 arch/arm/xen/enlighten.c     | 7 ++++---
 arch/x86/xen/enlighten.c     | 7 +++++++
 arch/x86/xen/enlighten_pv.c  | 1 +
 arch/x86/xen/enlighten_pvh.c | 1 +
 include/xen/xen.h            | 6 +++++-
 5 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index ba7f4c8f5c3e..a99d5edf7bdf 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -59,6 +59,9 @@ struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
 
 static __read_mostly unsigned int xen_events_irq;
 
+uint32_t xen_start_flags;
+EXPORT_SYMBOL(xen_start_flags);
+
 int xen_remap_domain_gfn_array(struct vm_area_struct *vma,
 			       unsigned long addr,
 			       xen_pfn_t *gfn, int nr,
@@ -282,9 +285,7 @@ void __init xen_early_init(void)
 	xen_setup_features();
 
 	if (xen_feature(XENFEAT_dom0))
-		xen_start_info->flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
-	else
-		xen_start_info->flags &= ~(SIF_INITDOMAIN|SIF_PRIVILEGED);
+		xen_start_flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
 
 	if (!console_set_on_cmdline && !xen_initial_domain())
 		add_preferred_console("hvc", 0, NULL);
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index c9081c6671f0..3b5318505c69 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -64,6 +64,13 @@ struct shared_info xen_dummy_shared_info;
 __read_mostly int xen_have_vector_callback;
 EXPORT_SYMBOL_GPL(xen_have_vector_callback);
 
+/*
+ * NB: needs to live in .data because it's used by xen_prepare_pvh which runs
+ * before clearing the bss.
+ */
+uint32_t xen_start_flags __attribute__((section(".data"))) = 0;
+EXPORT_SYMBOL(xen_start_flags);
+
 /*
  * Point at some empty memory to start with. We map the real shared_info
  * page as soon as fixmap is up and running.
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 357969a3697c..8d4e2e1ae60b 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1203,6 +1203,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 		return;
 
 	xen_domain_type = XEN_PV_DOMAIN;
+	xen_start_flags = xen_start_info->flags;
 
 	xen_setup_features();
 
diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c
index aa1c6a6831a9..c85d1a88f476 100644
--- a/arch/x86/xen/enlighten_pvh.c
+++ b/arch/x86/xen/enlighten_pvh.c
@@ -97,6 +97,7 @@ void __init xen_prepare_pvh(void)
 	}
 
 	xen_pvh = 1;
+	xen_start_flags = pvh_start_info.flags;
 
 	msr = cpuid_ebx(xen_cpuid_base() + 2);
 	pfn = __pa(hypercall_page);
diff --git a/include/xen/xen.h b/include/xen/xen.h
index 9d4340c907d1..1e1d9bd0bd37 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -25,12 +25,16 @@ extern bool xen_pvh;
 #define xen_hvm_domain()	(xen_domain_type == XEN_HVM_DOMAIN)
 #define xen_pvh_domain()	(xen_pvh)
 
+#include <linux/types.h>
+
+extern uint32_t xen_start_flags;
+
 #ifdef CONFIG_XEN_DOM0
 #include <xen/interface/xen.h>
 #include <asm/xen/hypervisor.h>
 
 #define xen_initial_domain()	(xen_domain() && \
-				 xen_start_info && xen_start_info->flags & SIF_INITDOMAIN)
+				 (xen_start_flags & SIF_INITDOMAIN))
 #else  /* !CONFIG_XEN_DOM0 */
 #define xen_initial_domain()	(0)
 #endif	/* CONFIG_XEN_DOM0 */
-- 
2.17.1