[Xen-devel] RFC: Nested VMX patch series 04: virtual VMCS structure and APIs

["Dong, Eddie" <eddie.dong@xxxxxxxxx>]

Virtual VMCS structure and access wrapper APIs

Thx, Eddie

        Signed-off-by: Qing He <qing.he@xxxxxxxxx>
        Signed-off-by: Eddie Dong <eddie.dong@xxxxxxxxx>

diff -r f0647d3c60dc xen/arch/x86/hvm/vmx/vvmx.c
--- a/xen/arch/x86/hvm/vmx/vvmx.c       Sat May 28 23:20:01 2011 +0800
+++ b/xen/arch/x86/hvm/vmx/vvmx.c       Mon May 30 15:07:17 2011 +0800
@@ -183,6 +183,84 @@
 #define CASE_GET_REG(REG, reg)      \
     case VMX_REG_ ## REG: value = regs->reg; break
 
+static int vvmcs_offset(u32 width, u32 type, u32 index)
+{
+    int offset;
+
+    offset = (index & 0x1f) | type << 5 | width << 7;
+
+    if ( offset == 0 )    /* vpid */
+        offset = 0x3f;
+
+    return offset;
+}
+
+u64 __get_vvmcs(void *vvmcs, u32 vmcs_encoding)
+{
+    union vmcs_encoding enc;
+    u64 *content = (u64 *) vvmcs;
+    int offset;
+    u64 res;
+
+    enc.word = vmcs_encoding;
+    offset = vvmcs_offset(enc.width, enc.type, enc.index);
+    res = content[offset];
+
+    switch ( enc.width ) {
+    case VVMCS_WIDTH_16:
+        res &= 0xffff;
+        break;
+   case VVMCS_WIDTH_64:
+        if ( enc.access_type )
+            res >>= 32;
+        break;
+    case VVMCS_WIDTH_32:
+        res &= 0xffffffff;
+        break;
+    case VVMCS_WIDTH_NATURAL:
+    default:
+        break;
+    }
+
+    return res;
+}
+
+void __set_vvmcs(void *vvmcs, u32 vmcs_encoding, u64 val)
+{
+    union vmcs_encoding enc;
+    u64 *content = (u64 *) vvmcs;
+    int offset;
+    u64 res;
+
+    enc.word = vmcs_encoding;
+    offset = vvmcs_offset(enc.width, enc.type, enc.index);
+    res = content[offset];
+
+    switch ( enc.width ) {
+    case VVMCS_WIDTH_16:
+        res = val & 0xffff;
+        break;
+    case VVMCS_WIDTH_64:
+        if ( enc.access_type )
+        {
+            res &= 0xffffffff;
+            res |= val << 32;
+        }
+        else
+            res = val;
+        break;
+    case VVMCS_WIDTH_32:
+        res = val & 0xffffffff;
+        break;
+    case VVMCS_WIDTH_NATURAL:
+    default:
+        res = val;
+        break;
+    }
+
+    content[offset] = res;
+}
+
 static unsigned long reg_read(struct cpu_user_regs *regs,
                               enum vmx_regs_enc index)
 {
diff -r f0647d3c60dc xen/include/asm-x86/hvm/vmx/vvmx.h
--- a/xen/include/asm-x86/hvm/vmx/vvmx.h        Sat May 28 23:20:01 2011 +0800
+++ b/xen/include/asm-x86/hvm/vmx/vvmx.h        Mon May 30 15:07:17 2011 +0800
@@ -23,6 +23,9 @@
 #ifndef __ASM_X86_HVM_VVMX_H__
 #define __ASM_X86_HVM_VVMX_H__
 
+#include <xen/config.h>
+#include <asm/types.h>
+
 struct vmcs_struct;
 
 struct nestedvmx {
@@ -48,5 +51,61 @@
 
 int nvmx_handle_vmxon(struct cpu_user_regs *regs);
 int nvmx_handle_vmxoff(struct cpu_user_regs *regs);
+/*
+ * Virtual VMCS layout
+ *
+ * Since physical VMCS layout is unknown, a custom layout is used
+ * for virtual VMCS seen by guest. It occupies a 4k page, and the
+ * field is offset by an 9-bit offset into u64[], The offset is as
+ * follow, which means every <width, type> pair has a max of 32
+ * fields available.
+ *
+ *             9       7      5               0
+ *             --------------------------------
+ *     offset: | width | type |     index     |
+ *             --------------------------------
+ *
+ * Also, since the lower range <width=0, type={0,1}> has only one
+ * field: VPID, it is moved to a higher offset (63), and leaves the
+ * lower range to non-indexed field like VMCS revision.
+ *
+ */
+
+#define VVMCS_REVISION 0x40000001u
+
+struct vvmcs_header {
+    u32 revision;
+    u32 abort;
+};
+
+union vmcs_encoding {
+    struct {
+        u32 access_type : 1;
+        u32 index : 9;
+        u32 type : 2;
+        u32 rsv1 : 1;
+        u32 width : 2;
+        u32 rsv2 : 17;
+    };
+    u32 word;
+};
+
+enum vvmcs_encoding_width {
+    VVMCS_WIDTH_16 = 0,
+    VVMCS_WIDTH_64,
+    VVMCS_WIDTH_32,
+    VVMCS_WIDTH_NATURAL,
+};
+
+enum vvmcs_encoding_type {
+    VVMCS_TYPE_CONTROL = 0,
+    VVMCS_TYPE_RO,
+    VVMCS_TYPE_GSTATE,
+    VVMCS_TYPE_HSTATE,
+};
+
+u64 __get_vvmcs(void *vvmcs, u32 vmcs_encoding);
+void __set_vvmcs(void *vvmcs, u32 vmcs_encoding, u64 val);
+
 #endif /* __ASM_X86_HVM_VVMX_H__ */


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