Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1695559

[PATCH 3/3] xen: fix hvm guest with kaslr enabled

Show all headers | View raw

A Xen HVM guest running with KASLR enabled will die rather soon today
due to the shared info page mapping is using va() too early. This was
introduced by commit a5d5f328b0e2baa5ee7c119fd66324eb79eeeb66 ("xen:
allocate page for shared info page from low memory").

In order to fix this use early_memremap() to get a temporary virtual
address for shared info until va() can be used safely.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/xen/enlighten_hvm.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index d23531f5f17e..de503c225ae1 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -12,6 +12,7 @@
 #include <asm/setup.h>
 #include <asm/hypervisor.h>
 #include <asm/e820/api.h>
+#include <asm/early_ioremap.h>
 
 #include <asm/xen/cpuid.h>
 #include <asm/xen/hypervisor.h>
@@ -21,6 +22,8 @@
 #include "mmu.h"
 #include "smp.h"
 
+static unsigned long shared_info_pfn;
+
 void xen_hvm_init_shared_info(void)
 {
 	struct xen_add_to_physmap xatp;
@@ -28,7 +31,7 @@ void xen_hvm_init_shared_info(void)
 	xatp.domid = DOMID_SELF;
 	xatp.idx = 0;
 	xatp.space = XENMAPSPACE_shared_info;
-	xatp.gpfn = virt_to_pfn(HYPERVISOR_shared_info);
+	xatp.gpfn = shared_info_pfn;
 	if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
 		BUG();
 }
@@ -51,8 +54,16 @@ static void __init reserve_shared_info(void)
 	     pa += PAGE_SIZE)
 		;
 
+	shared_info_pfn = PHYS_PFN(pa);
+
 	memblock_reserve(pa, PAGE_SIZE);
-	HYPERVISOR_shared_info = __va(pa);
+	HYPERVISOR_shared_info = early_memremap(pa, PAGE_SIZE);
+}
+
+static void __init xen_hvm_init_mem_mapping(void)
+{
+	early_memunmap(HYPERVISOR_shared_info, PAGE_SIZE);
+	HYPERVISOR_shared_info = __va(PFN_PHYS(shared_info_pfn));
 }
 
 static void __init init_hvm_pv_info(void)
@@ -221,5 +232,6 @@ const struct hypervisor_x86 x86_hyper_xen_hvm = {
 	.init_platform          = xen_hvm_guest_init,
 	.pin_vcpu               = xen_pin_vcpu,
 	.x2apic_available       = xen_x2apic_para_available,
+	.init_mem_mapping	= xen_hvm_init_mem_mapping,
 };
 EXPORT_SYMBOL(x86_hyper_xen_hvm);
-- 
2.12.3

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/3] fix xen hvm guest with kaslr enabled Juergen Gross <jgross@suse.com> - 2017-07-25 12:00 +0200
  [PATCH 3/3] xen: fix hvm guest with kaslr enabled Juergen Gross <jgross@suse.com> - 2017-07-25 12:00 +0200
  [PATCH 2/3] xen: split up xen_hvm_init_shared_info() Juergen Gross <jgross@suse.com> - 2017-07-25 12:00 +0200
    Re: [PATCH 2/3] xen: split up xen_hvm_init_shared_info() Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-07-25 16:20 +0200
      Re: [PATCH 2/3] xen: split up xen_hvm_init_shared_info() Juergen Gross <jgross@suse.com> - 2017-07-25 16:50 +0200

csiph-web