KVM: PPC: Book3S: Provide information about hardware/firmware CVE workarounds (3214d01f) · Commits · 戴 / test

Documentation/virtual/kvm/api.txt

+46 −0

Original line number	Diff line number	Diff line
		@@ -3403,6 +3403,52 @@ invalid, if invalid pages are written to (e.g. after the end of memory)
		or if no page table is present for the addresses (e.g. when using
		hugepages).

		4.108 KVM_PPC_GET_CPU_CHAR

		Capability: KVM_CAP_PPC_GET_CPU_CHAR
		Architectures: powerpc
		Type: vm ioctl
		Parameters: struct kvm_ppc_cpu_char (out)
		Returns: 0 on successful completion
		-EFAULT if struct kvm_ppc_cpu_char cannot be written

		This ioctl gives userspace information about certain characteristics
		of the CPU relating to speculative execution of instructions and
		possible information leakage resulting from speculative execution (see
		CVE-2017-5715, CVE-2017-5753 and CVE-2017-5754). The information is
		returned in struct kvm_ppc_cpu_char, which looks like this:

		struct kvm_ppc_cpu_char {
		__u64 character; /* characteristics of the CPU */
		__u64 behaviour; /* recommended software behaviour */
		__u64 character_mask; /* valid bits in character */
		__u64 behaviour_mask; /* valid bits in behaviour */
		};

		For extensibility, the character_mask and behaviour_mask fields
		indicate which bits of character and behaviour have been filled in by
		the kernel. If the set of defined bits is extended in future then
		userspace will be able to tell whether it is running on a kernel that
		knows about the new bits.

		The character field describes attributes of the CPU which can help
		with preventing inadvertent information disclosure - specifically,
		whether there is an instruction to flash-invalidate the L1 data cache
		(ori 30,30,0 or mtspr SPRN_TRIG2,rN), whether the L1 data cache is set
		to a mode where entries can only be used by the thread that created
		them, whether the bcctr[l] instruction prevents speculation, and
		whether a speculation barrier instruction (ori 31,31,0) is provided.

		The behaviour field describes actions that software should take to
		prevent inadvertent information disclosure, and thus describes which
		vulnerabilities the hardware is subject to; specifically whether the
		L1 data cache should be flushed when returning to user mode from the
		kernel, and whether a speculation barrier should be placed between an
		array bounds check and the array access.

		These fields use the same bit definitions as the new
		H_GET_CPU_CHARACTERISTICS hypercall.

		5. The kvm_run structure
		------------------------

arch/powerpc/include/uapi/asm/kvm.h

+25 −0

Original line number	Diff line number	Diff line
		@@ -443,6 +443,31 @@ struct kvm_ppc_rmmu_info {
		__u32 ap_encodings[8];
		};

		/* For KVM_PPC_GET_CPU_CHAR */
		struct kvm_ppc_cpu_char {
		__u64 character; /* characteristics of the CPU */
		__u64 behaviour; /* recommended software behaviour */
		__u64 character_mask; /* valid bits in character */
		__u64 behaviour_mask; /* valid bits in behaviour */
		};

		/*
		* Values for character and character_mask.
		* These are identical to the values used by H_GET_CPU_CHARACTERISTICS.
		*/
		#define KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 (1ULL << 63)
		#define KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED (1ULL << 62)
		#define KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 (1ULL << 61)
		#define KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 (1ULL << 60)
		#define KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV (1ULL << 59)
		#define KVM_PPC_CPU_CHAR_BR_HINT_HONOURED (1ULL << 58)
		#define KVM_PPC_CPU_CHAR_MTTRIG_THR_RECONF (1ULL << 57)
		#define KVM_PPC_CPU_CHAR_COUNT_CACHE_DIS (1ULL << 56)

		#define KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY (1ULL << 63)
		#define KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR (1ULL << 62)
		#define KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR (1ULL << 61)

		/* Per-vcpu XICS interrupt controller state */
		#define KVM_REG_PPC_ICP_STATE (KVM_REG_PPC \| KVM_REG_SIZE_U64 \| 0x8c)

arch/powerpc/kvm/powerpc.c

+131 −0

Original line number	Diff line number	Diff line
		@@ -39,6 +39,10 @@
		#include <asm/iommu.h>
		#include <asm/switch_to.h>
		#include <asm/xive.h>
		#ifdef CONFIG_PPC_PSERIES
		#include <asm/hvcall.h>
		#include <asm/plpar_wrappers.h>
		#endif

		#include "timing.h"
		#include "irq.h"
		@@ -548,6 +552,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
		#ifdef CONFIG_KVM_XICS
		case KVM_CAP_IRQ_XICS:
		#endif
		case KVM_CAP_PPC_GET_CPU_CHAR:
		r = 1;
		break;

		@@ -1759,6 +1764,124 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
		return r;
		}

		#ifdef CONFIG_PPC_BOOK3S_64
		/*
		* These functions check whether the underlying hardware is safe
		* against attacks based on observing the effects of speculatively
		* executed instructions, and whether it supplies instructions for
		* use in workarounds. The information comes from firmware, either
		* via the device tree on powernv platforms or from an hcall on
		* pseries platforms.
		*/
		#ifdef CONFIG_PPC_PSERIES
		static int pseries_get_cpu_char(struct kvm_ppc_cpu_char *cp)
		{
		struct h_cpu_char_result c;
		unsigned long rc;

		if (!machine_is(pseries))
		return -ENOTTY;

		rc = plpar_get_cpu_characteristics(&c);
		if (rc == H_SUCCESS) {
		cp->character = c.character;
		cp->behaviour = c.behaviour;
		cp->character_mask = KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 \|
		KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED \|
		KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 \|
		KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 \|
		KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV \|
		KVM_PPC_CPU_CHAR_BR_HINT_HONOURED \|
		KVM_PPC_CPU_CHAR_MTTRIG_THR_RECONF \|
		KVM_PPC_CPU_CHAR_COUNT_CACHE_DIS;
		cp->behaviour_mask = KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY \|
		KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR \|
		KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR;
		}
		return 0;
		}
		#else
		static int pseries_get_cpu_char(struct kvm_ppc_cpu_char *cp)
		{
		return -ENOTTY;
		}
		#endif

		static inline bool have_fw_feat(struct device_node *fw_features,
		const char state, const char name)
		{
		struct device_node *np;
		bool r = false;

		np = of_get_child_by_name(fw_features, name);
		if (np) {
		r = of_property_read_bool(np, state);
		of_node_put(np);
		}
		return r;
		}

		static int kvmppc_get_cpu_char(struct kvm_ppc_cpu_char *cp)
		{
		struct device_node np, fw_features;
		int r;

		memset(cp, 0, sizeof(*cp));
		r = pseries_get_cpu_char(cp);
		if (r != -ENOTTY)
		return r;

		np = of_find_node_by_name(NULL, "ibm,opal");
		if (np) {
		fw_features = of_get_child_by_name(np, "fw-features");
		of_node_put(np);
		if (!fw_features)
		return 0;
		if (have_fw_feat(fw_features, "enabled",
		"inst-spec-barrier-ori31,31,0"))
		cp->character \|= KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31;
		if (have_fw_feat(fw_features, "enabled",
		"fw-bcctrl-serialized"))
		cp->character \|= KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED;
		if (have_fw_feat(fw_features, "enabled",
		"inst-l1d-flush-ori30,30,0"))
		cp->character \|= KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30;
		if (have_fw_feat(fw_features, "enabled",
		"inst-l1d-flush-trig2"))
		cp->character \|= KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2;
		if (have_fw_feat(fw_features, "enabled",
		"fw-l1d-thread-split"))
		cp->character \|= KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV;
		if (have_fw_feat(fw_features, "enabled",
		"fw-count-cache-disabled"))
		cp->character \|= KVM_PPC_CPU_CHAR_COUNT_CACHE_DIS;
		cp->character_mask = KVM_PPC_CPU_CHAR_SPEC_BAR_ORI31 \|
		KVM_PPC_CPU_CHAR_BCCTRL_SERIALISED \|
		KVM_PPC_CPU_CHAR_L1D_FLUSH_ORI30 \|
		KVM_PPC_CPU_CHAR_L1D_FLUSH_TRIG2 \|
		KVM_PPC_CPU_CHAR_L1D_THREAD_PRIV \|
		KVM_PPC_CPU_CHAR_COUNT_CACHE_DIS;

		if (have_fw_feat(fw_features, "enabled",
		"speculation-policy-favor-security"))
		cp->behaviour \|= KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY;
		if (!have_fw_feat(fw_features, "disabled",
		"needs-l1d-flush-msr-pr-0-to-1"))
		cp->behaviour \|= KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR;
		if (!have_fw_feat(fw_features, "disabled",
		"needs-spec-barrier-for-bound-checks"))
		cp->behaviour \|= KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR;
		cp->behaviour_mask = KVM_PPC_CPU_BEHAV_FAVOUR_SECURITY \|
		KVM_PPC_CPU_BEHAV_L1D_FLUSH_PR \|
		KVM_PPC_CPU_BEHAV_BNDS_CHK_SPEC_BAR;

		of_node_put(fw_features);
		}

		return 0;
		}
		#endif

		long kvm_arch_vm_ioctl(struct file *filp,
		unsigned int ioctl, unsigned long arg)
		{
		@@ -1861,6 +1984,14 @@ long kvm_arch_vm_ioctl(struct file *filp,
		r = -EFAULT;
		break;
		}
		case KVM_PPC_GET_CPU_CHAR: {
		struct kvm_ppc_cpu_char cpuchar;

		r = kvmppc_get_cpu_char(&cpuchar);
		if (r >= 0 && copy_to_user(argp, &cpuchar, sizeof(cpuchar)))
		r = -EFAULT;
		break;
		}
		default: {
		struct kvm *kvm = filp->private_data;
		r = kvm->arch.kvm_ops->arch_vm_ioctl(filp, ioctl, arg);

include/uapi/linux/kvm.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -932,6 +932,7 @@ struct kvm_ppc_resize_hpt {
		#define KVM_CAP_HYPERV_SYNIC2 148
		#define KVM_CAP_HYPERV_VP_INDEX 149
		#define KVM_CAP_S390_AIS_MIGRATION 150
		#define KVM_CAP_PPC_GET_CPU_CHAR 151

		#ifdef KVM_CAP_IRQ_ROUTING

		@@ -1261,6 +1262,8 @@ struct kvm_s390_ucas_mapping {
		#define KVM_PPC_CONFIGURE_V3_MMU _IOW(KVMIO, 0xaf, struct kvm_ppc_mmuv3_cfg)
		/* Available with KVM_CAP_PPC_RADIX_MMU */
		#define KVM_PPC_GET_RMMU_INFO _IOW(KVMIO, 0xb0, struct kvm_ppc_rmmu_info)
		/* Available with KVM_CAP_PPC_GET_CPU_CHAR */
		#define KVM_PPC_GET_CPU_CHAR _IOR(KVMIO, 0xb1, struct kvm_ppc_cpu_char)

		/* ioctl for vm fd */
		#define KVM_CREATE_DEVICE _IOWR(KVMIO, 0xe0, struct kvm_create_device)

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