KVM: x86: Hypercall handling does not considers opsize correctly

Currently, the hypercall handling routine only considers LME as an indication
to whether the guest uses 32/64-bit mode. This is incosistent with hyperv
hypercalls handling and against the common sense of considering cs.l as well.
This patch uses is_64_bit_mode instead of is_long_mode for that matter. In
addition, the result is masked in respect to the guest execution mode. Last, it
changes kvm_hv_hypercall to use is_64_bit_mode as well to simplify the code.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 451d6acea808..874607ae0583 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5669,7 +5669,6 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
         u64 param, ingpa, outgpa, ret;
         uint16_t code, rep_idx, rep_cnt, res = HV_STATUS_SUCCESS, rep_done = 0;
         bool fast, longmode;
-        int cs_db, cs_l;
 
         /*
          * hypercall generates UD from non zero cpl and real mode
@@ -5680,8 +5679,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
                 return 0;
         }
 
-        kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
-        longmode = is_long_mode(vcpu) && cs_l == 1;
+        longmode = is_64_bit_mode(vcpu);
 
         if (!longmode) {
                 param = ((u64)kvm_register_read(vcpu, VCPU_REGS_RDX) << 32) |
@@ -5746,7 +5744,7 @@ static void kvm_pv_kick_cpu_op(struct kvm *kvm, unsigned long flags, int apicid)
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 {
         unsigned long nr, a0, a1, a2, a3, ret;
-        int r = 1;
+        int op_64_bit, r = 1;
 
         if (kvm_hv_hypercall_enabled(vcpu->kvm))
                 return kvm_hv_hypercall(vcpu);
@@ -5759,7 +5757,8 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 
         trace_kvm_hypercall(nr, a0, a1, a2, a3);
 
-        if (!is_long_mode(vcpu)) {
+        op_64_bit = is_64_bit_mode(vcpu);
+        if (!op_64_bit) {
                 nr &= 0xFFFFFFFF;
                 a0 &= 0xFFFFFFFF;
                 a1 &= 0xFFFFFFFF;
@@ -5785,6 +5784,8 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
                 break;
         }
 out:
+        if (!op_64_bit)
+                ret = (u32)ret;
         kvm_register_write(vcpu, VCPU_REGS_RAX, ret);
         ++vcpu->stat.hypercalls;
         return r;