KVM: Cleanup string I/O instruction emulation

Both vmx and svm decode the I/O instructions, and both botch the job,
requiring the instruction prefixes to be fetched in order to completely
decode the instruction.

So, if we see a string I/O instruction, use the x86 emulator to decode it,
as it already has all the prefix decoding machinery.

This patch defines ins/outs opcodes in x86_emulate.c and calls
emulate_instruction() from io_interception() (svm.c) and from handle_io()
(vmx.c).  It removes all vmx/svm prefix instruction decoders
(get_addr_size(), io_get_override(), io_address(), get_io_count())

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 12 insertions, 64 deletions

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 30c627d3b21d..044722bc1a7f 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1763,82 +1763,30 @@ static int handle_triple_fault(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
         return 0;
 }
 
-static int get_io_count(struct kvm_vcpu *vcpu, unsigned long *count)
-{
-        u64 inst;
-        gva_t rip;
-        int countr_size;
-        int i;
-
-        if ((vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_VM)) {
-                countr_size = 2;
-        } else {
-                u32 cs_ar = vmcs_read32(GUEST_CS_AR_BYTES);
-
-                countr_size = (cs_ar & AR_L_MASK) ? 8:
-                              (cs_ar & AR_DB_MASK) ? 4: 2;
-        }
-
-        rip =  vmcs_readl(GUEST_RIP);
-        if (countr_size != 8)
-                rip += vmcs_readl(GUEST_CS_BASE);
-
-        if (emulator_read_std(rip, &inst, sizeof(inst), vcpu) !=
-                                                        X86EMUL_CONTINUE)
-                return 0;
-
-        for (i = 0; i < sizeof(inst); i++) {
-                switch (((u8*)&inst)[i]) {
-                case 0xf0:
-                case 0xf2:
-                case 0xf3:
-                case 0x2e:
-                case 0x36:
-                case 0x3e:
-                case 0x26:
-                case 0x64:
-                case 0x65:
-                case 0x66:
-                        break;
-                case 0x67:
-                        countr_size = (countr_size == 2) ? 4: (countr_size >> 1);
-                default:
-                        goto done;
-                }
-        }
-        return 0;
-done:
-        countr_size *= 8;
-        *count = vcpu->regs[VCPU_REGS_RCX] & (~0ULL >> (64 - countr_size));
-        //printk("cx: %lx\n", vcpu->regs[VCPU_REGS_RCX]);
-        return 1;
-}
-
 static int handle_io(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
         u64 exit_qualification;
         int size, down, in, string, rep;
         unsigned port;
-        unsigned long count;
-        gva_t address;
 
         ++vcpu->stat.io_exits;
         exit_qualification = vmcs_read64(EXIT_QUALIFICATION);
-        in = (exit_qualification & 8) != 0;
-        size = (exit_qualification & 7) + 1;
         string = (exit_qualification & 16) != 0;
+
+        if (string) {
+                if (emulate_instruction(vcpu, kvm_run, 0, 0) == EMULATE_DO_MMIO)
+                        return 0;
+                return 1;
+        }
+
+        size = (exit_qualification & 7) + 1;
+        in = (exit_qualification & 8) != 0;
         down = (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_DF) != 0;
-        count = 1;
         rep = (exit_qualification & 32) != 0;
         port = exit_qualification >> 16;
-        address = 0;
-        if (string) {
-                if (rep && !get_io_count(vcpu, &count))
-                        return 1;
-                address = vmcs_readl(GUEST_LINEAR_ADDRESS);
-        }
-        return kvm_setup_pio(vcpu, kvm_run, in, size, count, string, down,
-                             address, rep, port);
+
+        return kvm_setup_pio(vcpu, kvm_run, in, size, 1, 0, down,
+                             0, rep, port);
 }
 
 static void