KVM: s390: Features and fixes for 5.2

- VSIE crypto fixes - new guest features for gen15 - disable halt polling for nested virtualization with overcommit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAABAgAGBQJcxrJmAAoJEBF7vIC1phx8EsEP/2mIUbtY9OmVCZNHX43ds5Jr WR51UA/cXQGzP1cqLrqIchjJ40J7KGYBqS+9MeOyUxX85HUvb5dGgUiIfDOmh8R7 YIHe3nkM0dcIRbeuSp48sA8rl817TNGSBg7GnUN+eaEvJ/U+WbLb1sry/0uZN6Tm 2iFkff+XgSeEfBmrlxiPVl5PGUxi6FtKQWDwhn+MRkvs4sdQBh1SBITMIrzMgDmQ GMd5olfLp3AZZV2yniFvZM9TSWvKobCCH6IVF0/mBchxkqmdjQaKdSCRO6a1pLDh 8PVBN7i+yipLURUMBuDCMxGDBINJgvvXkThB8N9K6+CanUc8KCc7l0EimS93s3DB FsutI/2mSFy/xJ4nk98VVp8WCbVftQLtyKUSytBiqCTSpg1gtFMMntCPAqlON4TV xHOaAnJjF4Lhvfm0QrxQ22bAmuju6WIh5WKG8D+s7yqcn7GZeDUYdeftWiGNteaf sJwX1Vq8H6iUac1mfp7UbfT+60UuiCkj/d9sY9eRBNlPPIX6V4UgZU4Xh8/rSMf3 qnN4RCBGIQqndUzRzaw7ZtAfNy5jBE1BABems49fy07kuPCzrg9tQqXlWxf/60Ad QKqZ3Q/hb4ixYQJ7TAqQZmq1D3NL8w+V9MthcILmEGfMYF4BZKJV39ZigbttRIcN ZuiS+8IfOWN1IXZ2zXL0 =mZyZ -----END PGP SIGNATURE----- Merge tag 'kvm-s390-next-5.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD KVM: s390: Features and fixes for 5.2 - VSIE crypto fixes - new guest features for gen15 - disable halt polling for nested virtualization with overcommit
2019-04-30 21:29:14 +02:00 · 2019-04-30 21:29:14 +02:00 · da8f0d97b2
--- a/Documentation/virtual/kvm/devices/vm.txt
+++ b/Documentation/virtual/kvm/devices/vm.txt
@ -141,7 +141,8 @@ struct kvm_s390_vm_cpu_subfunc {
       u8 pcc[16];           # valid with Message-Security-Assist-Extension 4
       u8 ppno[16];          # valid with Message-Security-Assist-Extension 5
       u8 kma[16];           # valid with Message-Security-Assist-Extension 8
-       u8 reserved[1808];    # reserved for future instructions
+       u8 kdsa[16];          # valid with Message-Security-Assist-Extension 9
+       u8 reserved[1792];    # reserved for future instructions
 };

 Parameters: address of a buffer to load the subfunction blocks from.
--- a/arch/s390/include/asm/cpacf.h
+++ b/arch/s390/include/asm/cpacf.h
@ -28,6 +28,7 @@
 #define CPACF_KMCTR		0xb92d		/* MSA4 */
 #define CPACF_PRNO		0xb93c		/* MSA5 */
 #define CPACF_KMA		0xb929		/* MSA8 */
+#define CPACF_KDSA		0xb93a		/* MSA9 */

 /*
 * En/decryption modifier bits
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@ -278,6 +278,7 @@ struct kvm_s390_sie_block {
 #define ECD_HOSTREGMGMT	0x20000000
 #define ECD_MEF		0x08000000
 #define ECD_ETOKENF	0x02000000
+#define ECD_ECC		0x00200000
 	__u32	ecd;			/* 0x01c8 */
 	__u8	reserved1cc[18];	/* 0x01cc */
 	__u64	pp;			/* 0x01de */
@ -312,6 +313,7 @@ struct kvm_vcpu_stat {
 	u64 halt_successful_poll;
 	u64 halt_attempted_poll;
 	u64 halt_poll_invalid;
+	u64 halt_no_poll_steal;
 	u64 halt_wakeup;
 	u64 instruction_lctl;
 	u64 instruction_lctlg;
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@ -152,7 +152,10 @@ struct kvm_s390_vm_cpu_subfunc {
 	__u8 pcc[16];		/* with MSA4 */
 	__u8 ppno[16];		/* with MSA5 */
 	__u8 kma[16];		/* with MSA8 */
-	__u8 reserved[1808];
+	__u8 kdsa[16];		/* with MSA9 */
+	__u8 sortl[32];		/* with STFLE.150 */
+	__u8 dfltcc[32];	/* with STFLE.151 */
+	__u8 reserved[1728];
 };

 /* kvm attributes for crypto */
--- a/arch/s390/kvm/Kconfig
+++ b/arch/s390/kvm/Kconfig
@ -31,6 +31,7 @@ config KVM
 	select HAVE_KVM_IRQFD
 	select HAVE_KVM_IRQ_ROUTING
 	select HAVE_KVM_INVALID_WAKEUPS
+	select HAVE_KVM_NO_POLL
 	select SRCU
 	select KVM_VFIO
 	---help---
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@ -14,6 +14,7 @@
 #include <linux/kvm_host.h>
 #include <linux/hrtimer.h>
 #include <linux/mmu_context.h>
+#include <linux/nospec.h>
 #include <linux/signal.h>
 #include <linux/slab.h>
 #include <linux/bitmap.h>
@ -2307,6 +2308,7 @@ static struct s390_io_adapter *get_io_adapter(struct kvm *kvm, unsigned int id)
 {
 	if (id >= MAX_S390_IO_ADAPTERS)
 		return NULL;
+	id = array_index_nospec(id, MAX_S390_IO_ADAPTERS);
 	return kvm->arch.adapters[id];
 }

@ -2320,8 +2322,13 @@ static int register_io_adapter(struct kvm_device *dev,
 			   (void __user *)attr->addr, sizeof(adapter_info)))
 		return -EFAULT;

-	if ((adapter_info.id >= MAX_S390_IO_ADAPTERS) ||
-	    (dev->kvm->arch.adapters[adapter_info.id] != NULL))
+	if (adapter_info.id >= MAX_S390_IO_ADAPTERS)
+		return -EINVAL;
+
+	adapter_info.id = array_index_nospec(adapter_info.id,
+					     MAX_S390_IO_ADAPTERS);
+
+	if (dev->kvm->arch.adapters[adapter_info.id] != NULL)
 		return -EINVAL;

 	adapter = kzalloc(sizeof(*adapter), GFP_KERNEL);
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@ -75,6 +75,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 	{ "halt_successful_poll", VCPU_STAT(halt_successful_poll) },
 	{ "halt_attempted_poll", VCPU_STAT(halt_attempted_poll) },
 	{ "halt_poll_invalid", VCPU_STAT(halt_poll_invalid) },
+	{ "halt_no_poll_steal", VCPU_STAT(halt_no_poll_steal) },
 	{ "halt_wakeup", VCPU_STAT(halt_wakeup) },
 	{ "instruction_lctlg", VCPU_STAT(instruction_lctlg) },
 	{ "instruction_lctl", VCPU_STAT(instruction_lctl) },
@ -177,6 +178,11 @@ static int hpage;
 module_param(hpage, int, 0444);
 MODULE_PARM_DESC(hpage, "1m huge page backing support");

+/* maximum percentage of steal time for polling.  >100 is treated like 100 */
+static u8 halt_poll_max_steal = 10;
+module_param(halt_poll_max_steal, byte, 0644);
+MODULE_PARM_DESC(hpage, "Maximum percentage of steal time to allow polling");
+
 /*
 * For now we handle at most 16 double words as this is what the s390 base
 * kernel handles and stores in the prefix page. If we ever need to go beyond
@ -321,6 +327,22 @@ static inline int plo_test_bit(unsigned char nr)
 	return cc == 0;
 }

+static inline void __insn32_query(unsigned int opcode, u8 query[32])
+{
+	register unsigned long r0 asm("0") = 0;	/* query function */
+	register unsigned long r1 asm("1") = (unsigned long) query;
+
+	asm volatile(
+		/* Parameter regs are ignored */
+		"	.insn	rrf,%[opc] << 16,2,4,6,0\n"
+		: "=m" (*query)
+		: "d" (r0), "a" (r1), [opc] "i" (opcode)
+		: "cc");
+}
+
+#define INSN_SORTL 0xb938
+#define INSN_DFLTCC 0xb939
+
 static void kvm_s390_cpu_feat_init(void)
 {
 	int i;
@ -368,6 +390,16 @@ static void kvm_s390_cpu_feat_init(void)
 		__cpacf_query(CPACF_KMA, (cpacf_mask_t *)
 			      kvm_s390_available_subfunc.kma);

+	if (test_facility(155)) /* MSA9 */
+		__cpacf_query(CPACF_KDSA, (cpacf_mask_t *)
+			      kvm_s390_available_subfunc.kdsa);
+
+	if (test_facility(150)) /* SORTL */
+		__insn32_query(INSN_SORTL, kvm_s390_available_subfunc.sortl);
+
+	if (test_facility(151)) /* DFLTCC */
+		__insn32_query(INSN_DFLTCC, kvm_s390_available_subfunc.dfltcc);
+
 	if (MACHINE_HAS_ESOP)
 		allow_cpu_feat(KVM_S390_VM_CPU_FEAT_ESOP);
 	/*
@ -654,6 +686,14 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
 				set_kvm_facility(kvm->arch.model.fac_mask, 135);
 				set_kvm_facility(kvm->arch.model.fac_list, 135);
 			}
+			if (test_facility(148)) {
+				set_kvm_facility(kvm->arch.model.fac_mask, 148);
+				set_kvm_facility(kvm->arch.model.fac_list, 148);
+			}
+			if (test_facility(152)) {
+				set_kvm_facility(kvm->arch.model.fac_mask, 152);
+				set_kvm_facility(kvm->arch.model.fac_list, 152);
+			}
 			r = 0;
 		} else
 			r = -EINVAL;
@ -1320,6 +1360,19 @@ static int kvm_s390_set_processor_subfunc(struct kvm *kvm,
 	VM_EVENT(kvm, 3, "SET: guest KMA    subfunc 0x%16.16lx.%16.16lx",
 		 ((unsigned long *) &kvm->arch.model.subfuncs.kma)[0],
 		 ((unsigned long *) &kvm->arch.model.subfuncs.kma)[1]);
+	VM_EVENT(kvm, 3, "SET: guest KDSA   subfunc 0x%16.16lx.%16.16lx",
+		 ((unsigned long *) &kvm->arch.model.subfuncs.kdsa)[0],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.kdsa)[1]);
+	VM_EVENT(kvm, 3, "SET: guest SORTL  subfunc 0x%16.16lx.%16.16lx.%16.16lx.%16.16lx",
+		 ((unsigned long *) &kvm->arch.model.subfuncs.sortl)[0],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.sortl)[1],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.sortl)[2],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.sortl)[3]);
+	VM_EVENT(kvm, 3, "SET: guest DFLTCC subfunc 0x%16.16lx.%16.16lx.%16.16lx.%16.16lx",
+		 ((unsigned long *) &kvm->arch.model.subfuncs.dfltcc)[0],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.dfltcc)[1],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.dfltcc)[2],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.dfltcc)[3]);

 	return 0;
 }
@ -1488,6 +1541,19 @@ static int kvm_s390_get_processor_subfunc(struct kvm *kvm,
 	VM_EVENT(kvm, 3, "GET: guest KMA    subfunc 0x%16.16lx.%16.16lx",
 		 ((unsigned long *) &kvm->arch.model.subfuncs.kma)[0],
 		 ((unsigned long *) &kvm->arch.model.subfuncs.kma)[1]);
+	VM_EVENT(kvm, 3, "GET: guest KDSA   subfunc 0x%16.16lx.%16.16lx",
+		 ((unsigned long *) &kvm->arch.model.subfuncs.kdsa)[0],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.kdsa)[1]);
+	VM_EVENT(kvm, 3, "GET: guest SORTL  subfunc 0x%16.16lx.%16.16lx.%16.16lx.%16.16lx",
+		 ((unsigned long *) &kvm->arch.model.subfuncs.sortl)[0],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.sortl)[1],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.sortl)[2],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.sortl)[3]);
+	VM_EVENT(kvm, 3, "GET: guest DFLTCC subfunc 0x%16.16lx.%16.16lx.%16.16lx.%16.16lx",
+		 ((unsigned long *) &kvm->arch.model.subfuncs.dfltcc)[0],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.dfltcc)[1],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.dfltcc)[2],
+		 ((unsigned long *) &kvm->arch.model.subfuncs.dfltcc)[3]);

 	return 0;
 }
@ -1543,6 +1609,19 @@ static int kvm_s390_get_machine_subfunc(struct kvm *kvm,
 	VM_EVENT(kvm, 3, "GET: host  KMA    subfunc 0x%16.16lx.%16.16lx",
 		 ((unsigned long *) &kvm_s390_available_subfunc.kma)[0],
 		 ((unsigned long *) &kvm_s390_available_subfunc.kma)[1]);
+	VM_EVENT(kvm, 3, "GET: host  KDSA   subfunc 0x%16.16lx.%16.16lx",
+		 ((unsigned long *) &kvm_s390_available_subfunc.kdsa)[0],
+		 ((unsigned long *) &kvm_s390_available_subfunc.kdsa)[1]);
+	VM_EVENT(kvm, 3, "GET: host  SORTL  subfunc 0x%16.16lx.%16.16lx.%16.16lx.%16.16lx",
+		 ((unsigned long *) &kvm_s390_available_subfunc.sortl)[0],
+		 ((unsigned long *) &kvm_s390_available_subfunc.sortl)[1],
+		 ((unsigned long *) &kvm_s390_available_subfunc.sortl)[2],
+		 ((unsigned long *) &kvm_s390_available_subfunc.sortl)[3]);
+	VM_EVENT(kvm, 3, "GET: host  DFLTCC subfunc 0x%16.16lx.%16.16lx.%16.16lx.%16.16lx",
+		 ((unsigned long *) &kvm_s390_available_subfunc.dfltcc)[0],
+		 ((unsigned long *) &kvm_s390_available_subfunc.dfltcc)[1],
+		 ((unsigned long *) &kvm_s390_available_subfunc.dfltcc)[2],
+		 ((unsigned long *) &kvm_s390_available_subfunc.dfltcc)[3]);

 	return 0;
 }
@ -2814,6 +2893,25 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
 	vcpu->arch.enabled_gmap = vcpu->arch.gmap;
 }

+static bool kvm_has_pckmo_subfunc(struct kvm *kvm, unsigned long nr)
+{
+	if (test_bit_inv(nr, (unsigned long *)&kvm->arch.model.subfuncs.pckmo) &&
+	    test_bit_inv(nr, (unsigned long *)&kvm_s390_available_subfunc.pckmo))
+		return true;
+	return false;
+}
+
+static bool kvm_has_pckmo_ecc(struct kvm *kvm)
+{
+	/* At least one ECC subfunction must be present */
+	return kvm_has_pckmo_subfunc(kvm, 32) ||
+	       kvm_has_pckmo_subfunc(kvm, 33) ||
+	       kvm_has_pckmo_subfunc(kvm, 34) ||
+	       kvm_has_pckmo_subfunc(kvm, 40) ||
+	       kvm_has_pckmo_subfunc(kvm, 41);
+
+}
+
 static void kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu)
 {
 	/*
@ -2826,13 +2924,19 @@ static void kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu)
 	vcpu->arch.sie_block->crycbd = vcpu->kvm->arch.crypto.crycbd;
 	vcpu->arch.sie_block->ecb3 &= ~(ECB3_AES | ECB3_DEA);
 	vcpu->arch.sie_block->eca &= ~ECA_APIE;
+	vcpu->arch.sie_block->ecd &= ~ECD_ECC;

 	if (vcpu->kvm->arch.crypto.apie)
 		vcpu->arch.sie_block->eca |= ECA_APIE;

 	/* Set up protected key support */
-	if (vcpu->kvm->arch.crypto.aes_kw)
+	if (vcpu->kvm->arch.crypto.aes_kw) {
 		vcpu->arch.sie_block->ecb3 |= ECB3_AES;
+		/* ecc is also wrapped with AES key */
+		if (kvm_has_pckmo_ecc(vcpu->kvm))
+			vcpu->arch.sie_block->ecd |= ECD_ECC;
+	}
+
 	if (vcpu->kvm->arch.crypto.dea_kw)
 		vcpu->arch.sie_block->ecb3 |= ECB3_DEA;
 }
@ -3065,6 +3169,17 @@ static void kvm_gmap_notifier(struct gmap *gmap, unsigned long start,
 	}
 }

+bool kvm_arch_no_poll(struct kvm_vcpu *vcpu)
+{
+	/* do not poll with more than halt_poll_max_steal percent of steal time */
+	if (S390_lowcore.avg_steal_timer * 100 / (TICK_USEC << 12) >=
+	    halt_poll_max_steal) {
+		vcpu->stat.halt_no_poll_steal++;
+		return true;
+	}
+	return false;
+}
+
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
 	/* kvm common code refers to this, but never calls it */
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@ -288,7 +288,9 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	const u32 crycb_addr = crycbd_o & 0x7ffffff8U;
 	unsigned long *b1, *b2;
 	u8 ecb3_flags;
+	u32 ecd_flags;
 	int apie_h;
+	int apie_s;
 	int key_msk = test_kvm_facility(vcpu->kvm, 76);
 	int fmt_o = crycbd_o & CRYCB_FORMAT_MASK;
 	int fmt_h = vcpu->arch.sie_block->crycbd & CRYCB_FORMAT_MASK;
@ -297,7 +299,8 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	scb_s->crycbd = 0;

 	apie_h = vcpu->arch.sie_block->eca & ECA_APIE;
-	if (!apie_h && (!key_msk || fmt_o == CRYCB_FORMAT0))
+	apie_s = apie_h & scb_o->eca;
+	if (!apie_s && (!key_msk || (fmt_o == CRYCB_FORMAT0)))
 		return 0;

 	if (!crycb_addr)
@ -308,7 +311,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 		    ((crycb_addr + 128) & PAGE_MASK))
 			return set_validity_icpt(scb_s, 0x003CU);

-	if (apie_h && (scb_o->eca & ECA_APIE)) {
+	if (apie_s) {
 		ret = setup_apcb(vcpu, &vsie_page->crycb, crycb_addr,
 				 vcpu->kvm->arch.crypto.crycb,
 				 fmt_o, fmt_h);
@ -320,7 +323,8 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	/* we may only allow it if enabled for guest 2 */
 	ecb3_flags = scb_o->ecb3 & vcpu->arch.sie_block->ecb3 &
 		     (ECB3_AES | ECB3_DEA);
-	if (!ecb3_flags)
+	ecd_flags = scb_o->ecd & vcpu->arch.sie_block->ecd & ECD_ECC;
+	if (!ecb3_flags && !ecd_flags)
 		goto end;

 	/* copy only the wrapping keys */
@ -329,6 +333,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 		return set_validity_icpt(scb_s, 0x0035U);

 	scb_s->ecb3 |= ecb3_flags;
+	scb_s->ecd |= ecd_flags;

 	/* xor both blocks in one run */
 	b1 = (unsigned long *) vsie_page->crycb.dea_wrapping_key_mask;
@ -339,7 +344,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 end:
 	switch (ret) {
 	case -EINVAL:
-		return set_validity_icpt(scb_s, 0x0020U);
+		return set_validity_icpt(scb_s, 0x0022U);
 	case -EFAULT:
 		return set_validity_icpt(scb_s, 0x0035U);
 	case -EACCES:
--- a/arch/s390/tools/gen_facilities.c
+++ b/arch/s390/tools/gen_facilities.c
@ -93,6 +93,9 @@ static struct facility_def facility_defs[] = {
 			131, /* enhanced-SOP 2 and side-effect */
 			139, /* multiple epoch facility */
 			146, /* msa extension 8 */
+			150, /* enhanced sort */
+			151, /* deflate conversion */
+			155, /* msa extension 9 */
 			-1  /* END */
 		}
 	},
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@ -1307,6 +1307,16 @@ static inline bool vcpu_valid_wakeup(struct kvm_vcpu *vcpu)
 }
 #endif /* CONFIG_HAVE_KVM_INVALID_WAKEUPS */

+#ifdef CONFIG_HAVE_KVM_NO_POLL
+/* Callback that tells if we must not poll */
+bool kvm_arch_no_poll(struct kvm_vcpu *vcpu);
+#else
+static inline bool kvm_arch_no_poll(struct kvm_vcpu *vcpu)
+{
+	return false;
+}
+#endif /* CONFIG_HAVE_KVM_NO_POLL */
+
 #ifdef CONFIG_HAVE_KVM_VCPU_ASYNC_IOCTL
 long kvm_arch_vcpu_async_ioctl(struct file *filp,
 			       unsigned int ioctl, unsigned long arg);
--- a/tools/arch/s390/include/uapi/asm/kvm.h
+++ b/tools/arch/s390/include/uapi/asm/kvm.h
@ -152,7 +152,8 @@ struct kvm_s390_vm_cpu_subfunc {
 	__u8 pcc[16];		/* with MSA4 */
 	__u8 ppno[16];		/* with MSA5 */
 	__u8 kma[16];		/* with MSA8 */
-	__u8 reserved[1808];
+	__u8 kdsa[16];		/* with MSA9 */
+	__u8 reserved[1792];
 };

 /* kvm attributes for crypto */
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@ -57,3 +57,6 @@ config HAVE_KVM_VCPU_ASYNC_IOCTL

 config HAVE_KVM_VCPU_RUN_PID_CHANGE
       bool
+
+config HAVE_KVM_NO_POLL
+       bool
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@ -2253,7 +2253,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
 	u64 block_ns;

 	start = cur = ktime_get();
-	if (vcpu->halt_poll_ns) {
+	if (vcpu->halt_poll_ns && !kvm_arch_no_poll(vcpu)) {
 		ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns);

 		++vcpu->stat.halt_attempted_poll;