[PATCH v3 7/8] KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2
From: Maxim Levitsky
Date: Mon Jun 07 2021 - 05:03:05 EST
This is a new version of KVM_GET_SREGS / KVM_SET_SREGS.
It has the following changes:
* Has flags for future extensions
* Has vcpu's PDPTS, which allows to save/restore them on migration.
* Lacks obsolete interrupt bitmap (done now via KVM_SET_VCPU_EVENTS)
New capability, KVM_CAP_SREGS2 is added to signal
the userspace of this ioctl.
Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
Documentation/virt/kvm/api.rst | 48 +++++++++++
arch/x86/include/uapi/asm/kvm.h | 13 +++
arch/x86/kvm/kvm_cache_regs.h | 5 ++
arch/x86/kvm/x86.c | 141 ++++++++++++++++++++++++++------
include/uapi/linux/kvm.h | 4 +
5 files changed, 184 insertions(+), 27 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 7fcb2fd38f42..292522fbf3ed 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -5034,6 +5034,54 @@ see KVM_XEN_VCPU_SET_ATTR above.
The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used
with the KVM_XEN_VCPU_GET_ATTR ioctl.
+
+4.131 KVM_GET_SREGS2
+------------------
+
+:Capability: KVM_CAP_SREGS2
+:Architectures: x86
+:Type: vcpu ioctl
+:Parameters: struct kvm_sregs2 (out)
+:Returns: 0 on success, -1 on error
+
+Reads special registers from the vcpu.
+This ioctl (when supported) replaces the KVM_GET_SREGS.
+
+::
+
+struct kvm_sregs2 {
+ /* out (KVM_GET_SREGS2) / in (KVM_SET_SREGS2) */
+ struct kvm_segment cs, ds, es, fs, gs, ss;
+ struct kvm_segment tr, ldt;
+ struct kvm_dtable gdt, idt;
+ __u64 cr0, cr2, cr3, cr4, cr8;
+ __u64 efer;
+ __u64 apic_base;
+ __u64 flags;
+ __u64 pdptrs[4];
+};
+
+flags values for ``kvm_sregs2``:
+
+``KVM_SREGS2_FLAGS_PDPTRS_VALID``
+
+ Indicates thats the struct contain valid PDPTR values.
+
+
+4.132 KVM_SET_SREGS2
+------------------
+
+:Capability: KVM_CAP_SREGS2
+:Architectures: x86
+:Type: vcpu ioctl
+:Parameters: struct kvm_sregs2 (in)
+:Returns: 0 on success, -1 on error
+
+Writes special registers into the vcpu.
+See KVM_GET_SREGS2 for the data structures.
+This ioctl (when supported) replaces the KVM_SET_SREGS.
+
+
5. The kvm_run structure
========================
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 0662f644aad9..a6c327f8ad9e 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -159,6 +159,19 @@ struct kvm_sregs {
__u64 interrupt_bitmap[(KVM_NR_INTERRUPTS + 63) / 64];
};
+struct kvm_sregs2 {
+ /* out (KVM_GET_SREGS2) / in (KVM_SET_SREGS2) */
+ struct kvm_segment cs, ds, es, fs, gs, ss;
+ struct kvm_segment tr, ldt;
+ struct kvm_dtable gdt, idt;
+ __u64 cr0, cr2, cr3, cr4, cr8;
+ __u64 efer;
+ __u64 apic_base;
+ __u64 flags;
+ __u64 pdptrs[4];
+};
+#define KVM_SREGS2_FLAGS_PDPTRS_VALID 1
+
/* for KVM_GET_FPU and KVM_SET_FPU */
struct kvm_fpu {
__u8 fpr[8][16];
diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index b8559b83c4ca..842a09711b80 100644
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -125,6 +125,11 @@ static inline u64 kvm_pdptr_read(struct kvm_vcpu *vcpu, int index)
return vcpu->arch.walk_mmu->pdptrs[index];
}
+static inline void kvm_pdptr_write(struct kvm_vcpu *vcpu, int index, u64 value)
+{
+ vcpu->arch.walk_mmu->pdptrs[index] = value;
+}
+
static inline ulong kvm_read_cr0_bits(struct kvm_vcpu *vcpu, ulong mask)
{
ulong tmask = mask & KVM_POSSIBLE_CR0_GUEST_BITS;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0be35c37c958..11260e83518f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -113,6 +113,9 @@ static void __kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags);
static void store_regs(struct kvm_vcpu *vcpu);
static int sync_regs(struct kvm_vcpu *vcpu);
+static int __set_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2);
+static void __get_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2);
+
struct kvm_x86_ops kvm_x86_ops __read_mostly;
EXPORT_SYMBOL_GPL(kvm_x86_ops);
@@ -812,7 +815,6 @@ int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3)
memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs));
kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
-
out:
return ret;
@@ -3862,6 +3864,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_SGX_ATTRIBUTE:
#endif
case KVM_CAP_VM_COPY_ENC_CONTEXT_FROM:
+ case KVM_CAP_SREGS2:
r = 1;
break;
case KVM_CAP_SET_GUEST_DEBUG2:
@@ -4778,6 +4781,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
void __user *argp = (void __user *)arg;
int r;
union {
+ struct kvm_sregs2 *sregs2;
struct kvm_lapic_state *lapic;
struct kvm_xsave *xsave;
struct kvm_xcrs *xcrs;
@@ -5150,6 +5154,28 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
break;
}
#endif
+ case KVM_GET_SREGS2: {
+ u.sregs2 = kzalloc(sizeof(struct kvm_sregs2), GFP_KERNEL);
+ r = -ENOMEM;
+ if (!u.sregs2)
+ goto out;
+ __get_sregs2(vcpu, u.sregs2);
+ r = -EFAULT;
+ if (copy_to_user(argp, u.sregs2, sizeof(struct kvm_sregs2)))
+ goto out;
+ r = 0;
+ break;
+ }
+ case KVM_SET_SREGS2: {
+ u.sregs2 = memdup_user(argp, sizeof(struct kvm_sregs2));
+ if (IS_ERR(u.sregs2)) {
+ r = PTR_ERR(u.sregs2);
+ u.sregs2 = NULL;
+ goto out;
+ }
+ r = __set_sregs2(vcpu, u.sregs2);
+ break;
+ }
default:
r = -EINVAL;
}
@@ -9793,7 +9819,7 @@ void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l)
}
EXPORT_SYMBOL_GPL(kvm_get_cs_db_l_bits);
-static void __get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
+static void __get_sregs_common(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
{
struct desc_ptr dt;
@@ -9826,14 +9852,36 @@ static void __get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
sregs->cr8 = kvm_get_cr8(vcpu);
sregs->efer = vcpu->arch.efer;
sregs->apic_base = kvm_get_apic_base(vcpu);
+}
- memset(sregs->interrupt_bitmap, 0, sizeof(sregs->interrupt_bitmap));
+static void __get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
+{
+ __get_sregs_common(vcpu, sregs);
+
+ if (vcpu->arch.guest_state_protected)
+ return;
if (vcpu->arch.interrupt.injected && !vcpu->arch.interrupt.soft)
set_bit(vcpu->arch.interrupt.nr,
(unsigned long *)sregs->interrupt_bitmap);
}
+static void __get_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2)
+{
+ int i;
+
+ __get_sregs_common(vcpu, (struct kvm_sregs *)sregs2);
+
+ if (vcpu->arch.guest_state_protected)
+ return;
+
+ if (is_pae_paging(vcpu)) {
+ for (i = 0 ; i < 4 ; i++)
+ sregs2->pdptrs[i] = kvm_pdptr_read(vcpu, i);
+ sregs2->flags |= KVM_SREGS2_FLAGS_PDPTRS_VALID;
+ }
+}
+
int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
struct kvm_sregs *sregs)
{
@@ -9945,24 +9993,23 @@ static bool kvm_is_valid_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
return kvm_is_valid_cr4(vcpu, sregs->cr4);
}
-static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
+static int __set_sregs_common(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs,
+ int *mmu_reset_needed, bool update_pdptrs)
{
struct msr_data apic_base_msr;
- int mmu_reset_needed = 0;
- int pending_vec, max_bits, idx;
+ int idx;
struct desc_ptr dt;
- int ret = -EINVAL;
if (!kvm_is_valid_sregs(vcpu, sregs))
- goto out;
+ return -EINVAL;
apic_base_msr.data = sregs->apic_base;
apic_base_msr.host_initiated = true;
if (kvm_set_apic_base(vcpu, &apic_base_msr))
- goto out;
+ return -EINVAL;
if (vcpu->arch.guest_state_protected)
- goto skip_protected_regs;
+ return 0;
dt.size = sregs->idt.limit;
dt.address = sregs->idt.base;
@@ -9972,31 +10019,30 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
static_call(kvm_x86_set_gdt)(vcpu, &dt);
vcpu->arch.cr2 = sregs->cr2;
- mmu_reset_needed |= kvm_read_cr3(vcpu) != sregs->cr3;
+ *mmu_reset_needed |= kvm_read_cr3(vcpu) != sregs->cr3;
vcpu->arch.cr3 = sregs->cr3;
kvm_register_mark_available(vcpu, VCPU_EXREG_CR3);
kvm_set_cr8(vcpu, sregs->cr8);
- mmu_reset_needed |= vcpu->arch.efer != sregs->efer;
+ *mmu_reset_needed |= vcpu->arch.efer != sregs->efer;
static_call(kvm_x86_set_efer)(vcpu, sregs->efer);
- mmu_reset_needed |= kvm_read_cr0(vcpu) != sregs->cr0;
+ *mmu_reset_needed |= kvm_read_cr0(vcpu) != sregs->cr0;
static_call(kvm_x86_set_cr0)(vcpu, sregs->cr0);
vcpu->arch.cr0 = sregs->cr0;
- mmu_reset_needed |= kvm_read_cr4(vcpu) != sregs->cr4;
+ *mmu_reset_needed |= kvm_read_cr4(vcpu) != sregs->cr4;
static_call(kvm_x86_set_cr4)(vcpu, sregs->cr4);
- idx = srcu_read_lock(&vcpu->kvm->srcu);
- if (is_pae_paging(vcpu)) {
- load_pdptrs(vcpu, vcpu->arch.walk_mmu, kvm_read_cr3(vcpu));
- mmu_reset_needed = 1;
+ if (update_pdptrs) {
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
+ if (is_pae_paging(vcpu)) {
+ load_pdptrs(vcpu, vcpu->arch.walk_mmu, kvm_read_cr3(vcpu));
+ *mmu_reset_needed = 1;
+ }
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
}
- srcu_read_unlock(&vcpu->kvm->srcu, idx);
-
- if (mmu_reset_needed)
- kvm_mmu_reset_context(vcpu);
kvm_set_segment(vcpu, &sregs->cs, VCPU_SREG_CS);
kvm_set_segment(vcpu, &sregs->ds, VCPU_SREG_DS);
@@ -10016,20 +10062,61 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
!is_protmode(vcpu))
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
-skip_protected_regs:
+ return 0;
+}
+
+static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
+{
+ int pending_vec, max_bits;
+ int mmu_reset_needed = 0;
+ int ret = __set_sregs_common(vcpu, sregs, &mmu_reset_needed, true);
+
+ if (ret)
+ return ret;
+
+ if (mmu_reset_needed)
+ kvm_mmu_reset_context(vcpu);
+
max_bits = KVM_NR_INTERRUPTS;
pending_vec = find_first_bit(
(const unsigned long *)sregs->interrupt_bitmap, max_bits);
+
if (pending_vec < max_bits) {
kvm_queue_interrupt(vcpu, pending_vec, false);
pr_debug("Set back pending irq %d\n", pending_vec);
+ kvm_make_request(KVM_REQ_EVENT, vcpu);
}
+ return 0;
+}
- kvm_make_request(KVM_REQ_EVENT, vcpu);
+static int __set_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2)
+{
+ int mmu_reset_needed = 0;
+ bool valid_pdptrs = sregs2->flags & KVM_SREGS2_FLAGS_PDPTRS_VALID;
+ int i, ret;
- ret = 0;
-out:
- return ret;
+ if (sregs2->flags & ~KVM_SREGS2_FLAGS_PDPTRS_VALID)
+ return -EINVAL;
+
+ ret = __set_sregs_common(vcpu, (struct kvm_sregs *)sregs2,
+ &mmu_reset_needed, !valid_pdptrs);
+ if (ret)
+ return ret;
+
+ if (valid_pdptrs) {
+ if (!is_pae_paging(vcpu))
+ return -EINVAL;
+ if (vcpu->arch.guest_state_protected)
+ return -EINVAL;
+ for (i = 0 ; i < 4 ; i++)
+ kvm_pdptr_write(vcpu, i, sregs2->pdptrs[i]);
+
+ kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
+ mmu_reset_needed = 1;
+ }
+ if (mmu_reset_needed)
+ kvm_mmu_reset_context(vcpu);
+ return 0;
}
int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 3fd9a7e9d90c..da98bc314ce0 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1082,6 +1082,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_SGX_ATTRIBUTE 196
#define KVM_CAP_VM_COPY_ENC_CONTEXT_FROM 197
#define KVM_CAP_PTP_KVM 198
+#define KVM_CAP_SREGS2 200
#ifdef KVM_CAP_IRQ_ROUTING
@@ -1620,6 +1621,9 @@ struct kvm_xen_hvm_attr {
#define KVM_XEN_VCPU_GET_ATTR _IOWR(KVMIO, 0xca, struct kvm_xen_vcpu_attr)
#define KVM_XEN_VCPU_SET_ATTR _IOW(KVMIO, 0xcb, struct kvm_xen_vcpu_attr)
+#define KVM_GET_SREGS2 _IOR(KVMIO, 0xcc, struct kvm_sregs2)
+#define KVM_SET_SREGS2 _IOW(KVMIO, 0xcd, struct kvm_sregs2)
+
struct kvm_xen_vcpu_attr {
__u16 type;
__u16 pad[3];
--
2.26.3