[PATCH v3 08/34] KVM: x86: hyper-v: Use HV_MAX_SPARSE_VCPU_BANKS/HV_VCPUS_PER_SPARSE_BANK instead of raw '64'

Vitaly Kuznetsov
2022-04-14T13:39:29Z

It may not be clear from where the '64' limit for the maximum sparse
bank number comes from, use HV_MAX_SPARSE_VCPU_BANKS define instead.
Use HV_VCPUS_PER_SPARSE_BANK in KVM_HV_MAX_SPARSE_VCPU_SET_BITS's
definition. Opportunistically adjust the comment around BUILD_BUG_ON().

No functional change.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/hyperv.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index fc4bb0ead9fa..3cf68645a2e6 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -43,7 +43,7 @@
/* "Hv#1" signature */
#define HYPERV_CPUID_SIGNATURE_EAX 0x31237648

-#define KVM_HV_MAX_SPARSE_VCPU_SET_BITS DIV_ROUND_UP(KVM_MAX_VCPUS, 64)
+#define KVM_HV_MAX_SPARSE_VCPU_SET_BITS DIV_ROUND_UP(KVM_MAX_VCPUS, HV_VCPUS_PER_SPARSE_BANK)

static void stimer_mark_pending(struct kvm_vcpu_hv_stimer *stimer,
bool vcpu_kick);
@@ -1798,7 +1798,7 @@ 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)
+ if (hc->var_cnt > HV_MAX_SPARSE_VCPU_BANKS)
return -EINVAL;

/* Cap var_cnt to ignore banks that cannot contain a legal VP index. */
@@ -1969,12 +1969,11 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
gpa_t data_offset;

/*
- * The Hyper-V TLFS doesn't allow more than 64 sparse banks, e.g. the
- * valid mask is a u64. Fail the build if KVM's max allowed number of
- * vCPUs (>4096) would exceed this limit, KVM will additional changes
- * for Hyper-V support to avoid setting the guest up to fail.
+ * The Hyper-V TLFS doesn't allow more than HV_MAX_SPARSE_VCPU_BANKS
+ * sparse banks. Fail the build if KVM's max allowed number of
+ * vCPUs (>4096) exceeds this limit.
*/
- BUILD_BUG_ON(KVM_HV_MAX_SPARSE_VCPU_SET_BITS > 64);
+ BUILD_BUG_ON(KVM_HV_MAX_SPARSE_VCPU_SET_BITS > HV_MAX_SPARSE_VCPU_BANKS);

if (!hc->fast && is_guest_mode(vcpu)) {
hc->ingpa = translate_nested_gpa(vcpu, hc->ingpa, 0, NULL);
--
2.35.1