Commit 29d24e3f authored by Radim Krčmář's avatar Radim Krčmář

Merge tag 'kvm-ppc-cve-4.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc

Add PPC KVM ioctl to report vulnerability and workaround status to userspace.
parents 37b95951 3214d01f
......@@ -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
------------------------
......
......@@ -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)
......
......@@ -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);
......
......@@ -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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