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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
	Arnd Bergmann <arnd@arndb.de>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-hyperv@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	Ajay Garg <ajaygargnsit@gmail.com>
Subject: [PATCH v2 2/8] KVM: x86: Get the number of Hyper-V sparse banks from the VARHEAD field
Date: Fri, 29 Oct 2021 17:07:54 -0700	[thread overview]
Message-ID: <20211030000800.3065132-3-seanjc@google.com> (raw)
In-Reply-To: <20211030000800.3065132-1-seanjc@google.com>

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.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/hyperv.c             | 35 ++++++++++++++++++-------------
 arch/x86/kvm/trace.h              | 14 +++++++------
 include/asm-generic/hyperv-tlfs.h |  1 +
 3 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 814d1a1f2cb8..cf18aa1712bf 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1742,6 +1742,7 @@ struct kvm_hv_hcall {
 	u64 ingpa;
 	u64 outgpa;
 	u16 code;
+	u16 var_cnt;
 	u16 rep_cnt;
 	u16 rep_idx;
 	bool fast;
@@ -1761,7 +1762,6 @@ 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) {
@@ -1811,24 +1811,28 @@ 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;
 			}
@@ -1884,7 +1888,6 @@ 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;
 
@@ -1917,22 +1920,25 @@ 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;
 	}
 
@@ -2190,13 +2196,14 @@ 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 953b0fcb21ee..f6625cfb686c 100644
--- 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 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 56348a541c50..1ba8e6da4427 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -182,6 +182,7 @@ 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)
-- 
2.33.1.1089.g2158813163f-goog


  parent reply	other threads:[~2021-10-30  0:08 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-30  0:07 [PATCH v2 0/8] KVM: x86: Hyper-V hypercall fix and cleanups Sean Christopherson
2021-10-30  0:07 ` [PATCH v2 1/8] KVM: x86: Ignore sparse banks size for an "all CPUs", non-sparse IPI req Sean Christopherson
2021-11-01  9:05   ` Vitaly Kuznetsov
2021-10-30  0:07 ` Sean Christopherson [this message]
2021-11-01  9:52   ` [PATCH v2 2/8] KVM: x86: Get the number of Hyper-V sparse banks from the VARHEAD field Vitaly Kuznetsov
2021-10-30  0:07 ` [PATCH v2 3/8] KVM: x86: Refactor kvm_hv_flush_tlb() to reduce indentation Sean Christopherson
2021-11-01 10:00   ` Vitaly Kuznetsov
2021-12-03 23:45     ` Sean Christopherson
2021-10-30  0:07 ` [PATCH v2 4/8] KVM: x86: Add a helper to get the sparse VP_SET for IPIs and TLB flushes Sean Christopherson
2021-11-01 10:06   ` Vitaly Kuznetsov
2021-10-30  0:07 ` [PATCH v2 5/8] KVM: x86: Don't bother reading sparse banks that end up being ignored Sean Christopherson
2021-11-01  9:46   ` Vitaly Kuznetsov
2021-10-30  0:07 ` [PATCH v2 6/8] KVM: x86: Shove vp_bitmap handling down into sparse_set_to_vcpu_mask() Sean Christopherson
2021-11-01 10:12   ` Vitaly Kuznetsov
2021-10-30  0:07 ` [PATCH v2 7/8] KVM: x86: Reject fixeds-size Hyper-V hypercalls with non-zero "var_cnt" Sean Christopherson
2021-11-01 10:27   ` Vitaly Kuznetsov
2021-12-03 23:48     ` Sean Christopherson
2021-10-30  0:08 ` [PATCH v2 8/8] KVM: x86: Add checks for reserved-to-zero Hyper-V hypercall fields Sean Christopherson
2021-11-01 10:33   ` Vitaly Kuznetsov
2021-12-02  2:13     ` Sean Christopherson
2021-12-02 15:16       ` Michael Kelley (LINUX)
2021-12-03 14:09         ` ** POTENTIAL FRAUD ALERT - RED HAT ** " Vitaly Kuznetsov

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