Changes from v1:
- get msrs and set msrs are now symmetric: both accept a list of msrs. it
is now possible to retrieve a single msr.
- a new KVM_GET_MSR_INDEX_LIST allows discovering which msrs are supported
by kvm (previously this was integrated into KVM_GET_MSRS)
- error handling is simpler and correcter
- the implementation is collapsed into a single msr_io() function
- avoid pointers in ioctl structs, instead use zero length arrays
Andrew, this patch replaces kvm-exposer-msrs-to-userspace.patch.
--
Expose the model-specific registers to userspace. Primarily useful for
save/resume.
Signed-off-by: Uri Lublin <[email protected]>
Signed-off-by: Avi Kivity <[email protected]>
Index: linux-2.6/drivers/kvm/kvm.h
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm.h
+++ linux-2.6/drivers/kvm/kvm.h
@@ -106,11 +106,7 @@ struct vmcs {
char data[0];
};
-struct vmx_msr_entry {
- u32 index;
- u32 reserved;
- u64 data;
-};
+#define vmx_msr_entry kvm_msr_entry
struct kvm_vcpu;
Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -129,6 +129,8 @@ static const u32 vmx_msr_index[] = {
#define MSR_IA32_VMX_EXIT_CTLS_MSR 0x483
#define MSR_IA32_VMX_ENTRY_CTLS_MSR 0x484
+#define MAX_IO_MSRS 256
+
#define CR0_RESEVED_BITS 0xffffffff1ffaffc0ULL
#define LMSW_GUEST_MASK 0x0eULL
#define CR4_RESEVED_BITS (~((1ULL << 11) - 1))
@@ -2298,21 +2300,22 @@ static int handle_cpuid(struct kvm_vcpu
return 0;
}
-static int handle_rdmsr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+/*
+ * Reads an msr value (of 'msr_index') into 'pdata'.
+ * Returns 0 on success, non-0 otherwise.
+ * Assumes vcpu_load() was already called.
+ */
+static int get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
{
- u32 ecx = vcpu->regs[VCPU_REGS_RCX];
- struct vmx_msr_entry *msr = find_msr_entry(vcpu, ecx);
u64 data;
+ struct vmx_msr_entry *msr;
-#ifdef KVM_DEBUG
- if (guest_cpl() != 0) {
- vcpu_printf(vcpu, "%s: not supervisor\n", __FUNCTION__);
- inject_gp(vcpu);
- return 1;
+ if (!pdata) {
+ printk(KERN_ERR "BUG: get_msr called with NULL pdata\n");
+ return -EINVAL;
}
-#endif
- switch (ecx) {
+ switch (msr_index) {
#ifdef __x86_64__
case MSR_FS_BASE:
data = vmcs_readl(GUEST_FS_BASE);
@@ -2351,11 +2354,25 @@ static int handle_rdmsr(struct kvm_vcpu
data = vcpu->apic_base;
break;
default:
- if (msr) {
- data = msr->data;
- break;
+ msr = find_msr_entry(vcpu, msr_index);
+ if (!msr) {
+ printk(KERN_ERR "kvm: unhandled rdmsr: %x\n", msr_index);
+ return 1;
}
- printk(KERN_ERR "kvm: unhandled rdmsr: %x\n", ecx);
+ data = msr->data;
+ break;
+ }
+
+ *pdata = data;
+ return 0;
+}
+
+static int handle_rdmsr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+ u32 ecx = vcpu->regs[VCPU_REGS_RCX];
+ u64 data;
+
+ if (get_msr(vcpu, ecx, &data)) {
inject_gp(vcpu);
return 1;
}
@@ -2401,22 +2418,16 @@ static void set_efer(struct kvm_vcpu *vc
#endif
-static int handle_wrmsr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+
+/*
+ * Writes msr value into into the appropriate "register".
+ * Returns 0 on success, non-0 otherwise.
+ * Assumes vcpu_load() was already called.
+ */
+static int set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
{
- u32 ecx = vcpu->regs[VCPU_REGS_RCX];
struct vmx_msr_entry *msr;
- u64 data = (vcpu->regs[VCPU_REGS_RAX] & -1u)
- | ((u64)(vcpu->regs[VCPU_REGS_RDX] & -1u) << 32);
-
-#ifdef KVM_DEBUG
- if (guest_cpl() != 0) {
- vcpu_printf(vcpu, "%s: not supervisor\n", __FUNCTION__);
- inject_gp(vcpu);
- return 1;
- }
-#endif
-
- switch (ecx) {
+ switch (msr_index) {
#ifdef __x86_64__
case MSR_FS_BASE:
vmcs_writel(GUEST_FS_BASE, data);
@@ -2437,7 +2448,7 @@ static int handle_wrmsr(struct kvm_vcpu
#ifdef __x86_64
case MSR_EFER:
set_efer(vcpu, data);
- return 1;
+ break;
case MSR_IA32_MC0_STATUS:
printk(KERN_WARNING "%s: MSR_IA32_MC0_STATUS 0x%llx, nop\n"
, __FUNCTION__, data);
@@ -2455,16 +2466,31 @@ static int handle_wrmsr(struct kvm_vcpu
vcpu->apic_base = data;
break;
default:
- msr = find_msr_entry(vcpu, ecx);
- if (msr) {
- msr->data = data;
- break;
+ msr = find_msr_entry(vcpu, msr_index);
+ if (!msr) {
+ printk(KERN_ERR "kvm: unhandled wrmsr: 0x%x\n", msr_index);
+ return 1;
}
- printk(KERN_ERR "kvm: unhandled wrmsr: %x\n", ecx);
+ msr->data = data;
+ break;
+ }
+
+ return 0;
+}
+
+static int handle_wrmsr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+ u32 ecx = vcpu->regs[VCPU_REGS_RCX];
+ u64 data = (vcpu->regs[VCPU_REGS_RAX] & -1u)
+ | ((u64)(vcpu->regs[VCPU_REGS_RDX] & -1u) << 32);
+
+ if (set_msr(vcpu, ecx, data) != 0) {
inject_gp(vcpu);
return 1;
}
- skip_emulated_instruction(vcpu);
+
+ if (ecx != MSR_EFER)
+ skip_emulated_instruction(vcpu);
return 1;
}
@@ -3121,6 +3147,106 @@ static int kvm_dev_ioctl_set_sregs(struc
}
/*
+ * List of msr numbers which we expose to userspace through KVM_GET_MSRS
+ * and KVM_SET_MSRS, and KVM_GET_MSR_INDEX_LIST.
+ */
+static u32 msrs_to_save[] = {
+ MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
+ MSR_K6_STAR,
+#ifdef __x86_64__
+ MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
+#endif
+ MSR_IA32_TIME_STAMP_COUNTER,
+};
+
+
+/*
+ * Adapt set_msr() to msr_io()'s calling convention
+ */
+static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data)
+{
+ return set_msr(vcpu, index, *data);
+}
+
+/*
+ * Read or write a bunch of msrs. All parameters are kernel addresses.
+ *
+ * @return number of msrs set successfully.
+ */
+static int __msr_io(struct kvm *kvm, struct kvm_msrs *msrs,
+ struct kvm_msr_entry *entries,
+ int (*do_msr)(struct kvm_vcpu *vcpu,
+ unsigned index, u64 *data))
+{
+ struct kvm_vcpu *vcpu;
+ int i;
+
+ if (msrs->vcpu < 0 || msrs->vcpu >= KVM_MAX_VCPUS)
+ return -EINVAL;
+
+ vcpu = vcpu_load(kvm, msrs->vcpu);
+ if (!vcpu)
+ return -ENOENT;
+
+ for (i = 0; i < msrs->nmsrs; ++i)
+ if (do_msr(vcpu, entries[i].index, &entries[i].data))
+ break;
+
+ vcpu_put(vcpu);
+
+ return i;
+}
+
+/*
+ * Read or write a bunch of msrs. Parameters are user addresses.
+ *
+ * @return number of msrs set successfully.
+ */
+static int msr_io(struct kvm *kvm, struct kvm_msrs __user *user_msrs,
+ int (*do_msr)(struct kvm_vcpu *vcpu,
+ unsigned index, u64 *data),
+ int writeback)
+{
+ struct kvm_msrs msrs;
+ struct kvm_msr_entry *entries;
+ int r, n;
+ unsigned size;
+
+ r = -EFAULT;
+ if (copy_from_user(&msrs, user_msrs, sizeof msrs))
+ goto out;
+
+ r = -E2BIG;
+ if (msrs.nmsrs >= MAX_IO_MSRS)
+ goto out;
+
+ r = -ENOMEM;
+ size = sizeof(struct kvm_msr_entry) * msrs.nmsrs;
+ entries = vmalloc(size);
+ if (!entries)
+ goto out;
+
+ r = -EFAULT;
+ if (copy_from_user(entries, user_msrs->entries, size))
+ goto out_free;
+
+ r = n = __msr_io(kvm, &msrs, entries, do_msr);
+ if (r < 0)
+ goto out_free;
+
+ r = -EFAULT;
+ if (writeback && copy_to_user(user_msrs->entries, entries, size))
+ goto out_free;
+
+ r = n;
+
+out_free:
+ vfree(entries);
+out:
+ return r;
+}
+
+/*
* Translate a guest virtual address to a guest physical address.
*/
static int kvm_dev_ioctl_translate(struct kvm *kvm, struct kvm_translation *tr)
@@ -3361,6 +3487,33 @@ static long kvm_dev_ioctl(struct file *f
goto out;
break;
}
+ case KVM_GET_MSRS:
+ r = msr_io(kvm, (void __user *)arg, get_msr, 1);
+ break;
+ case KVM_SET_MSRS:
+ r = msr_io(kvm, (void __user *)arg, do_set_msr, 0);
+ break;
+ case KVM_GET_MSR_INDEX_LIST: {
+ struct kvm_msr_list __user *user_msr_list = (void __user *)arg;
+ struct kvm_msr_list msr_list;
+ unsigned n;
+
+ r = -EFAULT;
+ if (copy_from_user(&msr_list, user_msr_list, sizeof msr_list))
+ goto out;
+ n = msr_list.nmsrs;
+ msr_list.nmsrs = ARRAY_SIZE(msrs_to_save);
+ if (copy_to_user(user_msr_list, &msr_list, sizeof msr_list))
+ goto out;
+ r = -E2BIG;
+ if (n < ARRAY_SIZE(msrs_to_save))
+ goto out;
+ r = -EFAULT;
+ if (copy_to_user(user_msr_list->indices, &msrs_to_save,
+ sizeof msrs_to_save))
+ goto out;
+ r = 0;
+ }
default:
;
}
Index: linux-2.6/include/linux/kvm.h
===================================================================
--- linux-2.6.orig/include/linux/kvm.h
+++ linux-2.6/include/linux/kvm.h
@@ -141,6 +141,26 @@ struct kvm_sregs {
__u64 interrupt_bitmap[KVM_IRQ_BITMAP_SIZE(__u64)];
};
+struct kvm_msr_entry {
+ __u32 index;
+ __u32 reserved;
+ __u64 data;
+};
+
+/* for KVM_GET_MSRS and KVM_SET_MSRS */
+struct kvm_msrs {
+ __u32 vcpu;
+ __u32 nmsrs; /* number of msrs in entries */
+
+ struct kvm_msr_entry entries[0];
+};
+
+/* for KVM_GET_MSR_INDEX_LIST */
+struct kvm_msr_list {
+ __u32 nmsrs; /* number of msrs in entries */
+ __u32 indices[0];
+};
+
/* for KVM_TRANSLATE */
struct kvm_translation {
/* in */
@@ -200,5 +220,8 @@ struct kvm_dirty_log {
#define KVM_SET_MEMORY_REGION _IOW(KVMIO, 10, struct kvm_memory_region)
#define KVM_CREATE_VCPU _IOW(KVMIO, 11, int /* vcpu_slot */)
#define KVM_GET_DIRTY_LOG _IOW(KVMIO, 12, struct kvm_dirty_log)
+#define KVM_GET_MSRS _IOWR(KVMIO, 13, struct kvm_msrs)
+#define KVM_SET_MSRS _IOWR(KVMIO, 14, struct kvm_msrs)
+#define KVM_GET_MSR_INDEX_LIST _IOWR(KVMIO, 15, struct kvm_msr_list)
#endif
-
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