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Date: Mon, 21 Apr 2014 15:20:14 -0400
From: Bandan Das <bsd@...hat.com>
To: kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Marcelo Tosatti <mtosatti@...hat.com>,
Gleb Natapov <gleb@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH v2] KVM: x86: Check for host supported fields in shadow vmcs
We track shadow vmcs fields through two static lists,
one for read only and another for r/w fields. However, with
addition of new vmcs fields, not all fields may be supported on
all hosts. If so, copy_vmcs12_to_shadow() trying to vmwrite on
unsupported hosts will result in a vmwrite error. For example, commit
36be0b9deb23161 introduced GUEST_BNDCFGS, which is not supported
by all processors. Filter out host unsupported fields before
letting guests use shadow vmcs
Signed-off-by: Bandan Das <bsd@...hat.com>
---
v2:
- Just compress the original lists instead of creating new ones
- Change commit message slightly to reflect this change
arch/x86/kvm/vmx.c | 54 ++++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 42 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7bed3e3..26a632f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -503,7 +503,7 @@ static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
[number##_HIGH] = VMCS12_OFFSET(name)+4
-static const unsigned long shadow_read_only_fields[] = {
+static unsigned long shadow_read_only_fields[] = {
/*
* We do NOT shadow fields that are modified when L0
* traps and emulates any vmx instruction (e.g. VMPTRLD,
@@ -526,10 +526,10 @@ static const unsigned long shadow_read_only_fields[] = {
GUEST_LINEAR_ADDRESS,
GUEST_PHYSICAL_ADDRESS
};
-static const int max_shadow_read_only_fields =
+static int max_shadow_read_only_fields =
ARRAY_SIZE(shadow_read_only_fields);
-static const unsigned long shadow_read_write_fields[] = {
+static unsigned long shadow_read_write_fields[] = {
GUEST_RIP,
GUEST_RSP,
GUEST_CR0,
@@ -558,7 +558,7 @@ static const unsigned long shadow_read_write_fields[] = {
HOST_FS_SELECTOR,
HOST_GS_SELECTOR
};
-static const int max_shadow_read_write_fields =
+static int max_shadow_read_write_fields =
ARRAY_SIZE(shadow_read_write_fields);
static const unsigned short vmcs_field_to_offset_table[] = {
@@ -3009,6 +3009,42 @@ static void free_kvm_area(void)
}
}
+static void init_vmcs_shadow_fields(void)
+{
+ int i, j;
+
+ /* No checks for read only fields yet */
+
+ for (i = j = 0; i < max_shadow_read_write_fields; i++) {
+
+ switch (shadow_read_write_fields[i]) {
+ case GUEST_BNDCFGS:
+ if (!vmx_mpx_supported())
+ continue;
+ break;
+ default:
+ break;
+ }
+
+ if (j < i)
+ shadow_read_write_fields[j] =
+ shadow_read_write_fields[i];
+ j++;
+ }
+ max_shadow_read_write_fields = j;
+
+ /* shadowed fields guest access without vmexit */
+ for (i = 0; i < max_shadow_read_write_fields; i++) {
+ clear_bit(shadow_read_write_fields[i],
+ vmx_vmwrite_bitmap);
+ clear_bit(shadow_read_write_fields[i],
+ vmx_vmread_bitmap);
+ }
+ for (i = 0; i < max_shadow_read_only_fields; i++)
+ clear_bit(shadow_read_only_fields[i],
+ vmx_vmread_bitmap);
+}
+
static __init int alloc_kvm_area(void)
{
int cpu;
@@ -3039,6 +3075,8 @@ static __init int hardware_setup(void)
enable_vpid = 0;
if (!cpu_has_vmx_shadow_vmcs())
enable_shadow_vmcs = 0;
+ if (enable_shadow_vmcs)
+ init_vmcs_shadow_fields();
if (!cpu_has_vmx_ept() ||
!cpu_has_vmx_ept_4levels()) {
@@ -8817,14 +8855,6 @@ static int __init vmx_init(void)
memset(vmx_vmread_bitmap, 0xff, PAGE_SIZE);
memset(vmx_vmwrite_bitmap, 0xff, PAGE_SIZE);
- /* shadowed read/write fields */
- for (i = 0; i < max_shadow_read_write_fields; i++) {
- clear_bit(shadow_read_write_fields[i], vmx_vmwrite_bitmap);
- clear_bit(shadow_read_write_fields[i], vmx_vmread_bitmap);
- }
- /* shadowed read only fields */
- for (i = 0; i < max_shadow_read_only_fields; i++)
- clear_bit(shadow_read_only_fields[i], vmx_vmread_bitmap);
/*
* Allow direct access to the PC debug port (it is often used for I/O
--
1.8.3.1
--
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