[PATCH v4 04/37] KVM: x86: hyper-v: Add helper to read hypercall data for array

Vitaly Kuznetsov
2022-05-25T09:02:00Z

From: Sean Christopherson <seanjc@google.com>

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>
---
arch/x86/kvm/hyperv.c | 53 +++++++++++++++++++++++++++----------------
1 file changed, 33 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index c8b22bf67577..762b0b699fdf 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1759,38 +1759,51 @@ 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)
@@ -1899,7 +1912,7 @@ 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;
@@ -2010,7 +2023,7 @@ 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;
--
2.35.3