KVM: x86: hyper-v: Add helper to read hypercall data for array

Move the guts of kvm_get_sparse_vp_set() to a helper so that the code for
reading a guest-provided array can be reused in the future, e.g. for
getting a list of virtual addresses whose TLB entries need to be flushed.

Opportunisticaly swap the order of the data and XMM adjustment so that
the XMM/gpa offsets are bundled together.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-11-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 9d9a5ff..3ba7e2d 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1753,38 +1753,51 @@ struct kvm_hv_hcall {
        sse128_t xmm[HV_HYPERCALL_MAX_XMM_REGISTERS];
 };
 
-static u64 kvm_get_sparse_vp_set(struct kvm *kvm, struct kvm_hv_hcall *hc,
-                                int consumed_xmm_halves,
-                                u64 *sparse_banks, gpa_t offset)
-{
-       u16 var_cnt;
-       int i;
 
-       if (hc->var_cnt > 64)
-               return -EINVAL;
-
-       /* Ignore banks that cannot possibly contain a legal VP index. */
-       var_cnt = min_t(u16, hc->var_cnt, KVM_HV_MAX_SPARSE_VCPU_SET_BITS);
+static int kvm_hv_get_hc_data(struct kvm *kvm, struct kvm_hv_hcall *hc,
+                             u16 orig_cnt, u16 cnt_cap, u64 *data,
+                             int consumed_xmm_halves, gpa_t offset)
+{
+       /*
+        * Preserve the original count when ignoring entries via a "cap", KVM
+        * still needs to validate the guest input (though the non-XMM path
+        * punts on the checks).
+        */
+       u16 cnt = min(orig_cnt, cnt_cap);
+       int i, j;
 
        if (hc->fast) {
                /*
                 * Each XMM holds two sparse banks, but do not count halves that
                 * have already been consumed for hypercall parameters.
                 */
-               if (hc->var_cnt > 2 * HV_HYPERCALL_MAX_XMM_REGISTERS - consumed_xmm_halves)
+               if (orig_cnt > 2 * HV_HYPERCALL_MAX_XMM_REGISTERS - consumed_xmm_halves)
                        return HV_STATUS_INVALID_HYPERCALL_INPUT;
-               for (i = 0; i < var_cnt; i++) {
-                       int j = i + consumed_xmm_halves;
+
+               for (i = 0; i < cnt; i++) {
+                       j = i + consumed_xmm_halves;
                        if (j % 2)
-                               sparse_banks[i] = sse128_hi(hc->xmm[j / 2]);
+                               data[i] = sse128_hi(hc->xmm[j / 2]);
                        else
-                               sparse_banks[i] = sse128_lo(hc->xmm[j / 2]);
+                               data[i] = sse128_lo(hc->xmm[j / 2]);
                }
                return 0;
        }
 
-       return kvm_read_guest(kvm, hc->ingpa + offset, sparse_banks,
-                             var_cnt * sizeof(*sparse_banks));
+       return kvm_read_guest(kvm, hc->ingpa + offset, data,
+                             cnt * sizeof(*data));
+}
+
+static u64 kvm_get_sparse_vp_set(struct kvm *kvm, struct kvm_hv_hcall *hc,
+                                u64 *sparse_banks, int consumed_xmm_halves,
+                                gpa_t offset)
+{
+       if (hc->var_cnt > 64)
+               return -EINVAL;
+
+       /* Cap var_cnt to ignore banks that cannot contain a legal VP index. */
+       return kvm_hv_get_hc_data(kvm, hc, hc->var_cnt, KVM_HV_MAX_SPARSE_VCPU_SET_BITS,
+                                 sparse_banks, consumed_xmm_halves, offset);
 }
 
 static void hv_tlb_flush_enqueue(struct kvm_vcpu *vcpu)
@@ -1895,7 +1908,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
                if (!hc->var_cnt)
                        goto ret_success;
 
-               if (kvm_get_sparse_vp_set(kvm, hc, 2, sparse_banks,
+               if (kvm_get_sparse_vp_set(kvm, hc, sparse_banks, 2,
                                          offsetof(struct hv_tlb_flush_ex,
                                                   hv_vp_set.bank_contents)))
                        return HV_STATUS_INVALID_HYPERCALL_INPUT;
@@ -2006,7 +2019,7 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
                if (!hc->var_cnt)
                        goto ret_success;
 
-               if (kvm_get_sparse_vp_set(kvm, hc, 1, sparse_banks,
+               if (kvm_get_sparse_vp_set(kvm, hc, sparse_banks, 1,
                                          offsetof(struct hv_send_ipi_ex,
                                                   vp_set.bank_contents)))
                        return HV_STATUS_INVALID_HYPERCALL_INPUT;