KVM: x86 emulator: Add check_perm callback

This patch adds a check_perm callback for each opcode into
the instruction emulator. This will be used to do all
necessary permission checks on instructions before checking
whether they are intercepted or not.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 1dbd0c7..460c2d8 100644 (file)
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -222,6 +222,7 @@ struct decode_cache {
        u8 seg_override;
        unsigned int d;
        int (*execute)(struct x86_emulate_ctxt *ctxt);
+       int (*check_perm)(struct x86_emulate_ctxt *ctxt);
        unsigned long regs[NR_VCPU_REGS];
        unsigned long eip;
        /* modrm */

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a2c31e5..4822824 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -111,6 +111,7 @@ struct opcode {
                struct group_dual *gdual;
                struct gprefix *gprefix;
        } u;
+       int (*check_perm)(struct x86_emulate_ctxt *ctxt);
 };
 
 struct group_dual {
@@ -2425,12 +2426,17 @@ static int em_movdqu(struct x86_emulate_ctxt *ctxt)
 
 #define D(_y) { .flags = (_y) }
 #define DI(_y, _i) { .flags = (_y), .intercept = x86_intercept_##_i }
+#define DIP(_y, _i, _p) { .flags = (_y), .intercept = x86_intercept_##_i, \
+                     .check_perm = (_p) }
 #define N    D(0)
 #define G(_f, _g) { .flags = ((_f) | Group), .u.group = (_g) }
 #define GD(_f, _g) { .flags = ((_f) | Group | GroupDual), .u.gdual = (_g) }
 #define I(_f, _e) { .flags = (_f), .u.execute = (_e) }
 #define II(_f, _e, _i) \
        { .flags = (_f), .u.execute = (_e), .intercept = x86_intercept_##_i }
+#define IIP(_f, _e, _i, _p) \
+       { .flags = (_f), .u.execute = (_e), .intercept = x86_intercept_##_i, \
+         .check_perm = (_p) }
 #define GP(_f, _g) { .flags = ((_f) | Prefix), .u.gprefix = (_g) }
 
 #define D2bv(_f)      D((_f) | ByteOp), D(_f)
@@ -2873,6 +2879,7 @@ done_prefixes:
        }
 
        c->execute = opcode.u.execute;
+       c->check_perm = opcode.check_perm;
        c->intercept = opcode.intercept;
 
        /* Unrecognised? */
@@ -3136,6 +3143,13 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
                goto done;
        }
 
+       /* Do instruction specific permission checks */
+       if (c->check_perm) {
+               rc = c->check_perm(ctxt);
+               if (rc != X86EMUL_CONTINUE)
+                       goto done;
+       }
+
        if (unlikely(ctxt->guest_mode) && c->intercept) {
                rc = ops->intercept(ctxt, c->intercept,
                                    X86_ICPT_POST_EXCEPT);