KVM: PPC: Book3S: Controls for in-kernel sPAPR hypercall handling

This provides a way for userspace controls which sPAPR hcalls get
handled in the kernel.  Each hcall can be individually enabled or
disabled for in-kernel handling, except for H_RTAS.  The exception
for H_RTAS is because userspace can already control whether
individual RTAS functions are handled in-kernel or not via the
KVM_PPC_RTAS_DEFINE_TOKEN ioctl, and because the numeric value for
H_RTAS is out of the normal sequence of hcall numbers.

Hcalls are enabled or disabled using the KVM_ENABLE_CAP ioctl for the
KVM_CAP_PPC_ENABLE_HCALL capability on the file descriptor for the VM.
The args field of the struct kvm_enable_cap specifies the hcall number
in args[0] and the enable/disable flag in args[1]; 0 means disable
in-kernel handling (so that the hcall will always cause an exit to
userspace) and 1 means enable.  Enabling or disabling in-kernel
handling of an hcall is effective across the whole VM.

The ability for KVM_ENABLE_CAP to be used on a VM file descriptor
on PowerPC is new, added by this commit.  The KVM_CAP_ENABLE_CAP_VM
capability advertises that this ability exists.

When a VM is created, an initial set of hcalls are enabled for
in-kernel handling.  The set that is enabled is the set that have
an in-kernel implementation at this point.  Any new hcall
implementations from this point onwards should not be added to the
default set without a good reason.

No distinction is made between real-mode and virtual-mode hcall
implementations; the one setting controls them both.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

10 files changed, 193 insertions, 2 deletions

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 0fe36497642c..5c54d196f4c8 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2863,8 +2863,8 @@ The fields in each entry are defined as follows:
          this function/index combination
 
 
-6. Capabilities that can be enabled
------------------------------------
+6. Capabilities that can be enabled on vCPUs
+--------------------------------------------
 
 There are certain capabilities that change the behavior of the virtual CPU when
 enabled. To enable them, please see section 4.37. Below you can find a list of
@@ -3002,3 +3002,40 @@ Parameters: args[0] is the XICS device fd
             args[1] is the XICS CPU number (server ID) for this vcpu
 
 This capability connects the vcpu to an in-kernel XICS device.
+
+
+7. Capabilities that can be enabled on VMs
+------------------------------------------
+
+There are certain capabilities that change the behavior of the virtual
+machine when enabled. To enable them, please see section 4.37. Below
+you can find a list of capabilities and what their effect on the VM
+is when enabling them.
+
+The following information is provided along with the description:
+
+  Architectures: which instruction set architectures provide this ioctl.
+      x86 includes both i386 and x86_64.
+
+  Parameters: what parameters are accepted by the capability.
+
+  Returns: the return value.  General error numbers (EBADF, ENOMEM, EINVAL)
+      are not detailed, but errors with specific meanings are.
+
+
+7.1 KVM_CAP_PPC_ENABLE_HCALL
+
+Architectures: ppc
+Parameters: args[0] is the sPAPR hcall number
+            args[1] is 0 to disable, 1 to enable in-kernel handling
+
+This capability controls whether individual sPAPR hypercalls (hcalls)
+get handled by the kernel or not.  Enabling or disabling in-kernel
+handling of an hcall is effective across the VM.  On creation, an
+initial set of hcalls are enabled for in-kernel handling, which
+consists of those hcalls for which in-kernel handlers were implemented
+before this capability was implemented.  If disabled, the kernel will
+not to attempt to handle the hcall, but will always exit to userspace
+to handle it.  Note that it may not make sense to enable some and
+disable others of a group of related hcalls, but KVM does not prevent
+userspace from doing that.
diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index a20cc0bbd048..052ab2ad49b5 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -187,6 +187,7 @@ extern void kvmppc_hv_entry_trampoline(void);
 extern u32 kvmppc_alignment_dsisr(struct kvm_vcpu *vcpu, unsigned int inst);
 extern ulong kvmppc_alignment_dar(struct kvm_vcpu *vcpu, unsigned int inst);
 extern int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd);
+extern void kvmppc_pr_init_default_hcalls(struct kvm *kvm);
 extern void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu,
                                  struct kvm_vcpu *vcpu);
 extern void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu,
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index f9ae69682ce1..62b2cee450a5 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -34,6 +34,7 @@
 #include <asm/processor.h>
 #include <asm/page.h>
 #include <asm/cacheflush.h>
+#include <asm/hvcall.h>
 
 #define KVM_MAX_VCPUS           NR_CPUS
 #define KVM_MAX_VCORES          NR_CPUS
@@ -263,6 +264,7 @@ struct kvm_arch {
 #ifdef CONFIG_PPC_BOOK3S_64
         struct list_head spapr_tce_tables;
         struct list_head rtas_tokens;
+        DECLARE_BITMAP(enabled_hcalls, MAX_HCALL_OPCODE/4 + 1);
 #endif
 #ifdef CONFIG_KVM_MPIC
         struct openpic *mpic;
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index f5995a912213..17ffcb4f27f9 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -493,6 +493,7 @@ int main(void)
         DEFINE(KVM_HOST_SDR1, offsetof(struct kvm, arch.host_sdr1));
         DEFINE(KVM_TLBIE_LOCK, offsetof(struct kvm, arch.tlbie_lock));
         DEFINE(KVM_NEED_FLUSH, offsetof(struct kvm, arch.need_tlb_flush.bits));
+        DEFINE(KVM_ENABLED_HCALLS, offsetof(struct kvm, arch.enabled_hcalls));
         DEFINE(KVM_LPCR, offsetof(struct kvm, arch.lpcr));
         DEFINE(KVM_RMOR, offsetof(struct kvm, arch.rmor));
         DEFINE(KVM_VRMA_SLB_V, offsetof(struct kvm, arch.vrma_slb_v));
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 1562acfa05bf..cf445d22570f 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -67,6 +67,8 @@
 /* Used as a "null" value for timebase values */
 #define TB_NIL  (~(u64)0)
 
+static DECLARE_BITMAP(default_enabled_hcalls, MAX_HCALL_OPCODE/4 + 1);
+
 static void kvmppc_end_cede(struct kvm_vcpu *vcpu);
 static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu);
 
@@ -562,6 +564,10 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
         struct kvm_vcpu *tvcpu;
         int idx, rc;
 
+        if (req <= MAX_HCALL_OPCODE &&
+            !test_bit(req/4, vcpu->kvm->arch.enabled_hcalls))
+                return RESUME_HOST;
+
         switch (req) {
         case H_ENTER:
                 idx = srcu_read_lock(&vcpu->kvm->srcu);
@@ -2269,6 +2275,10 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
          */
         cpumask_setall(&kvm->arch.need_tlb_flush);
 
+        /* Start out with the default set of hcalls enabled */
+        memcpy(kvm->arch.enabled_hcalls, default_enabled_hcalls,
+               sizeof(kvm->arch.enabled_hcalls));
+
         kvm->arch.rma = NULL;
 
         kvm->arch.host_sdr1 = mfspr(SPRN_SDR1);
@@ -2407,6 +2417,45 @@ static long kvm_arch_vm_ioctl_hv(struct file *filp,
         return r;
 }
 
+/*
+ * List of hcall numbers to enable by default.
+ * For compatibility with old userspace, we enable by default
+ * all hcalls that were implemented before the hcall-enabling
+ * facility was added.  Note this list should not include H_RTAS.
+ */
+static unsigned int default_hcall_list[] = {
+        H_REMOVE,
+        H_ENTER,
+        H_READ,
+        H_PROTECT,
+        H_BULK_REMOVE,
+        H_GET_TCE,
+        H_PUT_TCE,
+        H_SET_DABR,
+        H_SET_XDABR,
+        H_CEDE,
+        H_PROD,
+        H_CONFER,
+        H_REGISTER_VPA,
+#ifdef CONFIG_KVM_XICS
+        H_EOI,
+        H_CPPR,
+        H_IPI,
+        H_IPOLL,
+        H_XIRR,
+        H_XIRR_X,
+#endif
+        0
+};
+
+static void init_default_hcalls(void)
+{
+        int i;
+
+        for (i = 0; default_hcall_list[i]; ++i)
+                __set_bit(default_hcall_list[i] / 4, default_enabled_hcalls);
+}
+
 static struct kvmppc_ops kvm_ops_hv = {
         .get_sregs = kvm_arch_vcpu_ioctl_get_sregs_hv,
         .set_sregs = kvm_arch_vcpu_ioctl_set_sregs_hv,
@@ -2454,6 +2503,8 @@ static int kvmppc_book3s_init_hv(void)
         kvm_ops_hv.owner = THIS_MODULE;
         kvmppc_hv_ops = &kvm_ops_hv;
 
+        init_default_hcalls();
+
         r = kvmppc_mmu_hv_init();
         return r;
 }
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 64ac56f6c3fe..33aaadef7139 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1909,6 +1909,17 @@ hcall_try_real_mode:
         clrrdi  r3,r3,2
         cmpldi  r3,hcall_real_table_end - hcall_real_table
         bge     guest_exit_cont
+        /* See if this hcall is enabled for in-kernel handling */
+        ld      r4, VCPU_KVM(r9)
+        srdi    r0, r3, 8       /* r0 = (r3 / 4) >> 6 */
+        sldi    r0, r0, 3       /* index into kvm->arch.enabled_hcalls[] */
+        add     r4, r4, r0
+        ld      r0, KVM_ENABLED_HCALLS(r4)
+        rlwinm  r4, r3, 32-2, 0x3f      /* r4 = (r3 / 4) & 0x3f */
+        srd     r0, r0, r4
+        andi.   r0, r0, 1
+        beq     guest_exit_cont
+        /* Get pointer to handler, if any, and call it */
         LOAD_REG_ADDR(r4, hcall_real_table)
         lwax    r3,r3,r4
         cmpwi   r3,0
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 3b82e8616dfa..123ac7dc5e1f 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -1597,6 +1597,11 @@ static int kvmppc_core_init_vm_pr(struct kvm *kvm)
 {
         mutex_init(&kvm->arch.hpt_mutex);
 
+#ifdef CONFIG_PPC_BOOK3S_64
+        /* Start out with the default set of hcalls enabled */
+        kvmppc_pr_init_default_hcalls(kvm);
+#endif
+
         if (firmware_has_feature(FW_FEATURE_SET_MODE)) {
                 spin_lock(&kvm_global_user_count_lock);
                 if (++kvm_global_user_count == 1)
diff --git a/arch/powerpc/kvm/book3s_pr_papr.c b/arch/powerpc/kvm/book3s_pr_papr.c
index f7c25c625a5b..eacaa6e4876e 100644
--- a/arch/powerpc/kvm/book3s_pr_papr.c
+++ b/arch/powerpc/kvm/book3s_pr_papr.c
@@ -267,6 +267,10 @@ static int kvmppc_h_pr_xics_hcall(struct kvm_vcpu *vcpu, u32 cmd)
 
 int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd)
 {
+        if (cmd <= MAX_HCALL_OPCODE &&
+            !test_bit(cmd/4, vcpu->kvm->arch.enabled_hcalls))
+                return EMULATE_FAIL;
+
         switch (cmd) {
         case H_ENTER:
                 return kvmppc_h_pr_enter(vcpu);
@@ -304,3 +308,36 @@ int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd)
 
         return EMULATE_FAIL;
 }
+
+
+/*
+ * List of hcall numbers to enable by default.
+ * For compatibility with old userspace, we enable by default
+ * all hcalls that were implemented before the hcall-enabling
+ * facility was added.  Note this list should not include H_RTAS.
+ */
+static unsigned int default_hcall_list[] = {
+        H_ENTER,
+        H_REMOVE,
+        H_PROTECT,
+        H_BULK_REMOVE,
+        H_PUT_TCE,
+        H_CEDE,
+#ifdef CONFIG_KVM_XICS
+        H_XIRR,
+        H_CPPR,
+        H_EOI,
+        H_IPI,
+        H_IPOLL,
+        H_XIRR_X,
+#endif
+        0
+};
+
+void kvmppc_pr_init_default_hcalls(struct kvm *kvm)
+{
+        int i;
+
+        for (i = 0; default_hcall_list[i]; ++i)
+                __set_bit(default_hcall_list[i] / 4, kvm->arch.enabled_hcalls);
+}
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 61c738ab1283..3222a4d08a6f 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -387,6 +387,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_PPC_UNSET_IRQ:
         case KVM_CAP_PPC_IRQ_LEVEL:
         case KVM_CAP_ENABLE_CAP:
+        case KVM_CAP_ENABLE_CAP_VM:
         case KVM_CAP_ONE_REG:
         case KVM_CAP_IOEVENTFD:
         case KVM_CAP_DEVICE_CTRL:
@@ -417,6 +418,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_PPC_ALLOC_HTAB:
         case KVM_CAP_PPC_RTAS:
         case KVM_CAP_PPC_FIXUP_HCALL:
+        case KVM_CAP_PPC_ENABLE_HCALL:
 #ifdef CONFIG_KVM_XICS
         case KVM_CAP_IRQ_XICS:
 #endif
@@ -1099,6 +1101,40 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event,
         return 0;
 }
 
+
+static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
+                                   struct kvm_enable_cap *cap)
+{
+        int r;
+
+        if (cap->flags)
+                return -EINVAL;
+
+        switch (cap->cap) {
+#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
+        case KVM_CAP_PPC_ENABLE_HCALL: {
+                unsigned long hcall = cap->args[0];
+
+                r = -EINVAL;
+                if (hcall > MAX_HCALL_OPCODE || (hcall & 3) ||
+                    cap->args[1] > 1)
+                        break;
+                if (cap->args[1])
+                        set_bit(hcall / 4, kvm->arch.enabled_hcalls);
+                else
+                        clear_bit(hcall / 4, kvm->arch.enabled_hcalls);
+                r = 0;
+                break;
+        }
+#endif
+        default:
+                r = -EINVAL;
+                break;
+        }
+
+        return r;
+}
+
 long kvm_arch_vm_ioctl(struct file *filp,
                        unsigned int ioctl, unsigned long arg)
 {
@@ -1118,6 +1154,15 @@ long kvm_arch_vm_ioctl(struct file *filp,
 
                 break;
         }
+        case KVM_ENABLE_CAP:
+        {
+                struct kvm_enable_cap cap;
+                r = -EFAULT;
+                if (copy_from_user(&cap, argp, sizeof(cap)))
+                        goto out;
+                r = kvm_vm_ioctl_enable_cap(kvm, &cap);
+                break;
+        }
 #ifdef CONFIG_PPC_BOOK3S_64
         case KVM_CREATE_SPAPR_TCE: {
                 struct kvm_create_spapr_tce create_tce;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index e11d8f170a62..0418b746cb68 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -758,6 +758,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_VM_ATTRIBUTES 101
 #define KVM_CAP_ARM_PSCI_0_2 102
 #define KVM_CAP_PPC_FIXUP_HCALL 103
+#define KVM_CAP_PPC_ENABLE_HCALL 104
 
 #ifdef KVM_CAP_IRQ_ROUTING