[PATCH 04/15] KVM: x86 emulator: Add check_perm callback

[Joerg Roedel]

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.roe...@amd.com>
---
 arch/x86/include/asm/kvm_emulate.h |    1 +
 arch/x86/kvm/emulate.c             |   16 ++++++++++++++++
 2 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h 
b/arch/x86/include/asm/kvm_emulate.h
index 366de63..a891051 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -216,6 +216,7 @@ 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 b05e50d..f87d7f8 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -108,6 +108,7 @@ struct opcode {
                struct opcode *group;
                struct group_dual *gdual;
        } u;
+       int (*check_perm)(struct x86_emulate_ctxt *ctxt);
 };
 
 struct group_dual {
@@ -2328,14 +2329,21 @@ static int em_mov(struct x86_emulate_ctxt *ctxt)
 
 #define D(_y) { .flags = (_y) }
 #define DI(_y, _i) { .flags = (_y), .intercept = x86_intercept_##_i }
+#define DIP(_y, _i) { .flags = (_y), .intercept = x86_intercept_##_i, \
+                     .check_perm = em_check_perm_##_i }
 #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) \
+       { .flags = (_f), .u.execute = (_e), .intercept = x86_intercept_##_i, \
+         .check_perm = em_check_perm_##_i }
 
 #define D2bv(_f)      D((_f) | ByteOp), D(_f)
+#define D2bvI(_f, _i) DI((_f) | ByteOp, _i), DI((_f), _i)
+#define D2bvIP(_f, _i) DIP((_f) | ByteOp, _i), DIP((_f), _i)
 #define I2bv(_f, _e)  I((_f) | ByteOp, _e), I(_f, _e)
 
 #define D6ALU(_f) D2bv((_f) | DstMem | SrcReg | ModRM),                        
\
@@ -2751,6 +2759,7 @@ done_prefixes:
        }
 
        c->execute = opcode.u.execute;
+       c->check_perm = opcode.check_perm;
        c->intercept = opcode.intercept;
 
        /* Unrecognised? */
@@ -2999,6 +3008,13 @@ 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);
-- 
1.7.1


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