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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
36be0b9deb 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@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Bandan Das 2014-04-21 15:20:14 -04:00 committed by Paolo Bonzini
parent e8e249d78e
commit fe2b201b3b
1 changed files with 41 additions and 12 deletions
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53
arch/x86/kvm/vmx.c
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@ -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 +3009,41 @@ 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 +3074,8 @@ 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()) {
@ -8803,14 +8840,6 @@ 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