Il 19/04/2014 19:34, Bandan Das ha scritto:
We track shadow vmcs fields through two static lists,
one for read only fields and another for r/w. 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 older
hosts will result in a vmwrite error. For example, commit
36be0b9deb23161 introduced GUEST_BNDCFGS, which is not supported
for all processors. Create new lists based out of intersection of
static lists and host support and use them for tracking
shadow fields instead
Signed-off-by: Bandan Das <bsd@xxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 98 +++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 79 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7bed3e3..ffc2232 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -502,7 +502,10 @@ static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
#define FIELD64(number, name) [number] = VMCS12_OFFSET(name), \
[number##_HIGH] = VMCS12_OFFSET(name)+4
-
+/*
+ * Do not use the two lists below directly
+ * Use vmcs_shadow_fields instead
+ */
static const unsigned long shadow_read_only_fields[] = {
/*
* We do NOT shadow fields that are modified when L0
@@ -526,8 +529,6 @@ static const unsigned long shadow_read_only_fields[] = {
GUEST_LINEAR_ADDRESS,
GUEST_PHYSICAL_ADDRESS
};
-static const int max_shadow_read_only_fields =
- ARRAY_SIZE(shadow_read_only_fields);
static const unsigned long shadow_read_write_fields[] = {
GUEST_RIP,
@@ -558,8 +559,18 @@ static const unsigned long shadow_read_write_fields[] = {
HOST_FS_SELECTOR,
HOST_GS_SELECTOR
};
-static const int max_shadow_read_write_fields =
- ARRAY_SIZE(shadow_read_write_fields);
Can we just remove the "const" here, and compress the arrays down
similar to what kvm_init_msr_list does.
+/* If new shadow fields are added, these should be modified appropriately */
+#define VMCS_MAX_RO_FIELDS 10
+#define VMCS_MAX_RW_FIELDS 30
+
+struct vmcs_shadow_fields_data {
+ int shadow_ro_fields_len;
+ int shadow_rw_fields_len;
+ unsigned long shadow_read_only_fields[VMCS_MAX_RO_FIELDS];
+ unsigned long shadow_read_write_fields[VMCS_MAX_RW_FIELDS];
+};
+static struct vmcs_shadow_fields_data vmcs_shadow_fields;
static const unsigned short vmcs_field_to_offset_table[] = {
FIELD(VIRTUAL_PROCESSOR_ID, virtual_processor_id),
@@ -3027,6 +3038,56 @@ static __init int alloc_kvm_area(void)
return 0;
}
+static void cleanup_vmcs_shadow_fields(void)
+{
+ memset(&vmcs_shadow_fields, 0,
+ sizeof(struct vmcs_shadow_fields_data));
+}
+
+static void init_vmcs_shadow_fields(void)
+{
+ struct vmcs_shadow_fields_data *vmcs_ptr = &vmcs_shadow_fields;
+ int max_shadow_read_write_fields = ARRAY_SIZE(shadow_read_write_fields);
+ int max_shadow_read_only_fields = ARRAY_SIZE(shadow_read_only_fields);
+ int i, j;
+
+ for (i = 0, j = 0; i < max_shadow_read_write_fields; i++) {
+ if (i >= VMCS_MAX_RW_FIELDS) {
+ WARN(1, "Shadow RW fields index out of bounds\n");
+ break;
+ }
+ if ((shadow_read_write_fields[i] == GUEST_BNDCFGS) &&
+ !vmx_mpx_supported())
+ continue;
Please code this as a "switch" statement for easier future
extensibility. Again, this would be similar to kvm_init_msr_list.
How did you find this? Do you have access to a machine with shadow
VMCS? Is that Ivy Bridge Xeon E5 or does some lower-end Haswell have it?
Paolo
+ vmcs_ptr->shadow_read_write_fields[j++] =
+ shadow_read_write_fields[i];
+ vmcs_ptr->shadow_rw_fields_len++;
+ }
+
+ for (i = 0, j = 0; i < max_shadow_read_only_fields; i++) {
+ if (i >= VMCS_MAX_RO_FIELDS) {
+ WARN(1, "Shadow RO fields index out of bounds\n");
+ break;
+ }
+ vmcs_ptr->shadow_read_only_fields[j++] =
+ shadow_read_only_fields[i];
+ vmcs_ptr->shadow_ro_fields_len++;
+ }
+
+ /* shadowed read/write fields */
+ for (i = 0; i < vmcs_ptr->shadow_rw_fields_len; i++) {
+ clear_bit(vmcs_ptr->shadow_read_write_fields[i],
+ vmx_vmwrite_bitmap);
+ clear_bit(vmcs_ptr->shadow_read_write_fields[i],
+ vmx_vmread_bitmap);
+ }
+ /* shadowed read only fields */
+ for (i = 0; i < vmcs_ptr->shadow_ro_fields_len; i++)
+ clear_bit(vmcs_ptr->shadow_read_only_fields[i],
+ vmx_vmread_bitmap);
+
+}
+
static __init int hardware_setup(void)
{
if (setup_vmcs_config(&vmcs_config) < 0)
@@ -3039,6 +3100,8 @@ 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()) {
@@ -3084,6 +3147,8 @@ static __init int hardware_setup(void)
static __exit void hardware_unsetup(void)
{
+ if (enable_shadow_vmcs)
+ cleanup_vmcs_shadow_fields();
free_kvm_area();
}
@@ -6159,8 +6224,9 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx)
unsigned long field;
u64 field_value;
struct vmcs *shadow_vmcs = vmx->nested.current_shadow_vmcs;
- const unsigned long *fields = shadow_read_write_fields;
- const int num_fields = max_shadow_read_write_fields;
+ const unsigned long *fields =
+ vmcs_shadow_fields.shadow_read_write_fields;
+ const int num_fields = vmcs_shadow_fields.shadow_rw_fields_len;
vmcs_load(shadow_vmcs);
@@ -6189,13 +6255,15 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx)
static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
{
+ struct vmcs_shadow_fields_data *ptr = &vmcs_shadow_fields;
+
const unsigned long *fields[] = {
- shadow_read_write_fields,
- shadow_read_only_fields
+ ptr->shadow_read_write_fields,
+ ptr->shadow_read_only_fields
};
const int max_fields[] = {
- max_shadow_read_write_fields,
- max_shadow_read_only_fields
+ ptr->shadow_rw_fields_len,
+ ptr->shadow_ro_fields_len
};
int i, q;
unsigned long field;
@@ -8817,14 +8885,6 @@ 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
--
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