KVM: x86: Get the number of Hyper-V sparse banks from the VARHEAD field

Get the number of sparse banks from the VARHEAD field, which the guest is
required to provide as "The size of a variable header, in QWORDS.", where
the variable header is:

  Variable Header Bytes = {Total Header Bytes - sizeof(Fixed Header)}
                          rounded up to nearest multiple of 8
  Variable HeaderSize = Variable Header Bytes / 8

In other words, the VARHEAD should match the number of sparse banks.
Keep the manual count as a sanity check, but otherwise rely on the field
so as to more closely align with the logic defined in the TLFS and to
allow for future cleanups.

Tweak the tracepoint output to use "rep_cnt" instead of simply "cnt" now
that there is also "var_cnt".

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 0bc7488f2b39bd18419915ac9f491eb28dace695..d02398c7a22d62dfc2ab951875fcfd813d231ea6 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1746,6 +1746,7 @@ struct kvm_hv_hcall {
        u64 ingpa;
        u64 outgpa;
        u16 code;
+       u16 var_cnt;
        u16 rep_cnt;
        u16 rep_idx;
        bool fast;
@@ -1765,7 +1766,6 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
        unsigned long *vcpu_mask;
        u64 valid_bank_mask;
        u64 sparse_banks[64];
-       int sparse_banks_len;
        bool all_cpus;
 
        if (!ex) {
@@ -1815,24 +1815,28 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
                all_cpus = flush_ex.hv_vp_set.format !=
                        HV_GENERIC_SET_SPARSE_4K;
 
-               sparse_banks_len = bitmap_weight((unsigned long *)&valid_bank_mask, 64);
+               if (hc->var_cnt != bitmap_weight((unsigned long *)&valid_bank_mask, 64))
+                       return HV_STATUS_INVALID_HYPERCALL_INPUT;
 
-               if (!sparse_banks_len && !all_cpus)
+               if (!hc->var_cnt && !all_cpus)
                        goto ret_success;
 
                if (!all_cpus) {
                        if (hc->fast) {
-                               if (sparse_banks_len > HV_HYPERCALL_MAX_XMM_REGISTERS - 1)
+                               if (hc->var_cnt > HV_HYPERCALL_MAX_XMM_REGISTERS - 1)
                                        return HV_STATUS_INVALID_HYPERCALL_INPUT;
-                               for (i = 0; i < sparse_banks_len; i += 2) {
+                               for (i = 0; i < hc->var_cnt; i += 2) {
                                        sparse_banks[i] = sse128_lo(hc->xmm[i / 2 + 1]);
                                        sparse_banks[i + 1] = sse128_hi(hc->xmm[i / 2 + 1]);
                                }
                        } else {
+                               if (hc->var_cnt > 64)
+                                       return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
                                gpa = hc->ingpa + offsetof(struct hv_tlb_flush_ex,
                                                           hv_vp_set.bank_contents);
                                if (unlikely(kvm_read_guest(kvm, gpa, sparse_banks,
-                                                           sparse_banks_len *
+                                                           hc->var_cnt *
                                                            sizeof(sparse_banks[0]))))
                                        return HV_STATUS_INVALID_HYPERCALL_INPUT;
                        }
@@ -1888,7 +1892,6 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
        unsigned long *vcpu_mask;
        unsigned long valid_bank_mask;
        u64 sparse_banks[64];
-       int sparse_banks_len;
        u32 vector;
        bool all_cpus;
 
@@ -1921,22 +1924,25 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc, bool
 
                vector = send_ipi_ex.vector;
                valid_bank_mask = send_ipi_ex.vp_set.valid_bank_mask;
-               sparse_banks_len = bitmap_weight(&valid_bank_mask, 64) *
-                       sizeof(sparse_banks[0]);
-
                all_cpus = send_ipi_ex.vp_set.format == HV_GENERIC_SET_ALL;
 
+               if (hc->var_cnt != bitmap_weight(&valid_bank_mask, 64))
+                       return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
                if (all_cpus)
                        goto check_and_send_ipi;
 
-               if (!sparse_banks_len)
+               if (!hc->var_cnt)
                        goto ret_success;
 
+               if (hc->var_cnt > 64)
+                       return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
                if (kvm_read_guest(kvm,
                                   hc->ingpa + offsetof(struct hv_send_ipi_ex,
                                                        vp_set.bank_contents),
                                   sparse_banks,
-                                  sparse_banks_len))
+                                  hc->var_cnt * sizeof(sparse_banks[0])))
                        return HV_STATUS_INVALID_HYPERCALL_INPUT;
        }
 
@@ -2194,13 +2200,14 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
        }
 
        hc.code = hc.param & 0xffff;
+       hc.var_cnt = (hc.param & HV_HYPERCALL_VARHEAD_MASK) >> HV_HYPERCALL_VARHEAD_OFFSET;
        hc.fast = !!(hc.param & HV_HYPERCALL_FAST_BIT);
        hc.rep_cnt = (hc.param >> HV_HYPERCALL_REP_COMP_OFFSET) & 0xfff;
        hc.rep_idx = (hc.param >> HV_HYPERCALL_REP_START_OFFSET) & 0xfff;
        hc.rep = !!(hc.rep_cnt || hc.rep_idx);
 
-       trace_kvm_hv_hypercall(hc.code, hc.fast, hc.rep_cnt, hc.rep_idx,
-                              hc.ingpa, hc.outgpa);
+       trace_kvm_hv_hypercall(hc.code, hc.fast, hc.var_cnt, hc.rep_cnt,
+                              hc.rep_idx, hc.ingpa, hc.outgpa);
 
        if (unlikely(!hv_check_hypercall_access(hv_vcpu, hc.code))) {
                ret = HV_STATUS_ACCESS_DENIED;

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 92e6f6702f0061ef73da592a30c1350554175efa..e5a8c271b42d9a5345d4419ba894229bd382ac5e 100644 (file)
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -64,9 +64,9 @@ TRACE_EVENT(kvm_hypercall,
  * Tracepoint for hypercall.
  */
 TRACE_EVENT(kvm_hv_hypercall,
-       TP_PROTO(__u16 code, bool fast, __u16 rep_cnt, __u16 rep_idx,
-                __u64 ingpa, __u64 outgpa),
-       TP_ARGS(code, fast, rep_cnt, rep_idx, ingpa, outgpa),
+       TP_PROTO(__u16 code, bool fast,  __u16 var_cnt, __u16 rep_cnt,
+                __u16 rep_idx, __u64 ingpa, __u64 outgpa),
+       TP_ARGS(code, fast, var_cnt, rep_cnt, rep_idx, ingpa, outgpa),
 
        TP_STRUCT__entry(
                __field(        __u16,          rep_cnt         )
@@ -74,6 +74,7 @@ TRACE_EVENT(kvm_hv_hypercall,
                __field(        __u64,          ingpa           )
                __field(        __u64,          outgpa          )
                __field(        __u16,          code            )
+               __field(        __u16,          var_cnt         )
                __field(        bool,           fast            )
        ),
 
@@ -83,13 +84,14 @@ TRACE_EVENT(kvm_hv_hypercall,
                __entry->ingpa          = ingpa;
                __entry->outgpa         = outgpa;
                __entry->code           = code;
+               __entry->var_cnt        = var_cnt;
                __entry->fast           = fast;
        ),
 
-       TP_printk("code 0x%x %s cnt 0x%x idx 0x%x in 0x%llx out 0x%llx",
+       TP_printk("code 0x%x %s var_cnt 0x%x rep_cnt 0x%x idx 0x%x in 0x%llx out 0x%llx",
                  __entry->code, __entry->fast ? "fast" : "slow",
-                 __entry->rep_cnt, __entry->rep_idx,  __entry->ingpa,
-                 __entry->outgpa)
+                 __entry->var_cnt, __entry->rep_cnt, __entry->rep_idx,
+                 __entry->ingpa, __entry->outgpa)
 );
 
 TRACE_EVENT(kvm_hv_hypercall_done,

diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 8f97c2927beea1db6896bc5bfff84c710a02b610..b8babc4d3fe439a47357705de0b5d3b1712abcb9 100644 (file)
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -183,6 +183,7 @@ enum HV_GENERIC_SET_FORMAT {
 #define HV_HYPERCALL_RESULT_MASK       GENMASK_ULL(15, 0)
 #define HV_HYPERCALL_FAST_BIT          BIT(16)
 #define HV_HYPERCALL_VARHEAD_OFFSET    17
+#define HV_HYPERCALL_VARHEAD_MASK      GENMASK_ULL(26, 17)
 #define HV_HYPERCALL_REP_COMP_OFFSET   32
 #define HV_HYPERCALL_REP_COMP_1                BIT_ULL(32)
 #define HV_HYPERCALL_REP_COMP_MASK     GENMASK_ULL(43, 32)