On Thu, 12 Jul 2012 11:27:34 +0200, Marc Zyngier <marc.zyngier at arm.com> wrote:
> From: Rusty Russell [rusty.russell at linaro.org] Sent: Thursday, July 12,
> 2012 6:54 AM
>
> > Hi all,
> >
> > This turned out to be a longer patch series than I expected.
> > The idea is that qemu tells us exactly what CPU (and cpu features) the
> > guest should have, and we tell it exactly what CP15 registers we have.
> >
> > This allows us to be futureproof: if we want to emulate an A9 in
> > future, this interface would let us do that. If a future host CPU can
> > create a guest environment which looks like an A15, we can do that, too.
>
> Brilliant! Is there a corresponding Qemu patch somewhere? I'd love to give
> this a spin...
I have a terrible hack to check it works, see below; I wanted to discuss
the transition with Peter before writing something decent. Or let him
do the qemu side :)
If you don't apply the final patch, then you just need the
kvm_arch_init_vcpu() call to KVM_SET_SREGS. If we ignore the return
value, then it works with older kernels too.
Cheers,
Rusty.
diff --git a/linux-headers/asm-arm/kvm.h b/linux-headers/asm-arm/kvm.h
index 38ff1d6..988890a 100644
--- a/linux-headers/asm-arm/kvm.h
+++ b/linux-headers/asm-arm/kvm.h
@@ -66,7 +66,13 @@ struct kvm_regs {
};
+/* Supported Processor Types */
+#define KVM_ARM_TARGET_CORTEX_A15 (0xC0F)
+
struct kvm_sregs {
+ __u32 target;
+ __u32 num_features;
+ __u32 features[14];
};
struct kvm_fpu {
diff --git a/target-arm/kvm.c b/target-arm/kvm.c
index 29bb51f..650c9b3 100644
--- a/target-arm/kvm.c
+++ b/target-arm/kvm.c
@@ -32,8 +32,153 @@ int kvm_arch_init(KVMState *s)
return 0;
}
+/* Exactly like x86. */
+struct kvm_msr_entry {
+ __u32 index;
+ __u32 reserved;
+ __u64 data;
+};
+
+/* for KVM_GET_MSRS and KVM_SET_MSRS */
+struct kvm_msrs {
+ __u32 nmsrs; /* number of msrs in entries */
+ __u32 pad;
+
+ 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];
+};
+
+/* If you need to interpret the index values, here's the key. */
+#define KVM_ARM_MSR_COPROC_MASK 0xFFFF0000
+#define KVM_ARM_MSR_64_BIT_MASK 0x00008000
+#define KVM_ARM_MSR_64_OPC1_MASK 0x000000F0
+#define KVM_ARM_MSR_64_CRM_MASK 0x0000000F
+#define KVM_ARM_MSR_32_CRM_MASK 0x0000000F
+#define KVM_ARM_MSR_32_OPC2_MASK 0x00000070
+#define KVM_ARM_MSR_32_CRN_MASK 0x00000780
+#define KVM_ARM_MSR_32_OPC1_MASK 0x00003800
+
+static void print_index(__u32 idx)
+{
+ int coproc, opc1, crm, crn, opc2;
+ coproc = (idx & KVM_ARM_MSR_COPROC_MASK) >> 16;
+ if (coproc > 15) {
+ printf("Special (%u) => %u",
+ coproc, idx & ~KVM_ARM_MSR_COPROC_MASK);
+ } else if (idx & KVM_ARM_MSR_64_BIT_MASK) {
+ opc1 = (idx & KVM_ARM_MSR_64_OPC1_MASK) >> 4;
+ crm = idx & KVM_ARM_MSR_64_CRM_MASK;
+ printf("cp%u CRm(%u) Op1(%u)", coproc, crm, opc1);
+ } else {
+ opc1 = (idx & KVM_ARM_MSR_32_OPC1_MASK) >> 11;
+ crn = (idx & KVM_ARM_MSR_32_CRN_MASK) >> 7;
+ opc2 = (idx & KVM_ARM_MSR_32_OPC2_MASK) >> 4;
+ crm = idx & KVM_ARM_MSR_32_CRM_MASK;
+ printf("cp%u CRn(%u) CRm(%u) Op1(%u) Op2(%u)",
+ coproc, crn, crm, opc1, opc2);
+ }
+}
+
+static void play_with_msrs(CPUARMState *env)
+{
+ int ret, i;
+ struct kvm_msr_list *list = malloc(4096);
+ struct kvm_msrs *msrs;
+
+ list->nmsrs = 1;
+
+ ret = kvm_vcpu_ioctl(env, KVM_GET_MSR_INDEX_LIST, list);
+ printf("KVM_GET_MSR_INDEX_LIST(nmsrs=1) => %u, %s\n",
+ list->nmsrs, strerror(-ret));
+
+ if (ret == -EINVAL)
+ return;
+
+ assert(ret == -E2BIG);
+
+ list->nmsrs = 1023;
+ ret = kvm_vcpu_ioctl(env, KVM_GET_MSR_INDEX_LIST, list);
+ printf("KVM_GET_MSR_INDEX_LIST(nmsrs=1023) => %u, %s\n",
+ list->nmsrs, strerror(-ret));
+ assert(ret == 0);
+
+ for (i = 0; i < list->nmsrs; i++) {
+ printf(" ");
+ print_index(list->indices[i]);
+ printf("\n");
+ }
+
+ msrs = malloc(sizeof(*msrs) + sizeof(msrs->entries[0])*list->nmsrs);
+
+ /* Test invalid set/get */
+ msrs->nmsrs = 1;
+ msrs->entries[0].index = 0xDEADBEEF;
+
+ ret = kvm_vcpu_ioctl(env, KVM_GET_MSRS, msrs);
+ printf("KVM_GET_MSRS(nmsrs=1,entry[0]=0xDEADBEEF) => %s\n",
+ strerror(-ret));
+ assert(ret == -EINVAL);
+ ret = kvm_vcpu_ioctl(env, KVM_SET_MSRS, msrs);
+ printf("KVM_SET_MSRS(nmsrs=1,entry[0]=0xDEADBEEF) => %s\n",
+ strerror(-ret));
+ assert(ret == -EINVAL);
+
+ msrs->nmsrs = list->nmsrs;
+ for (i = 0; i < list->nmsrs; i++)
+ msrs->entries[i].index = list->indices[i];
+
+ ret = kvm_vcpu_ioctl(env, KVM_GET_MSRS, msrs);
+ printf("KVM_GET_MSRS(nmsrs=%u) => %s\n",
+ list->nmsrs, strerror(-ret));
+ assert(ret == 0);
+ assert(msrs->nmsrs == list->nmsrs);
+
+ for (i = 0; i < msrs->nmsrs; i++) {
+ print_index(msrs->entries[i].index);
+ printf(" = 0x%llx\n", (long long)msrs->entries[i].data);
+ }
+
+ ret = kvm_vcpu_ioctl(env, KVM_SET_MSRS, msrs);
+ printf("KVM_SET_MSRS(nmsrs=%u) => %s\n",
+ msrs->nmsrs, strerror(-ret));
+ assert(ret == 0);
+
+ /* Should not be able to change a fixed value. */
+ msrs->entries[0].data ^= 1;
+ ret = kvm_vcpu_ioctl(env, KVM_SET_MSRS, msrs);
+ printf("KVM_SET_MSRS(nmsrs=%u,entries[0]=changed) => %s\n",
+ msrs->nmsrs, strerror(-ret));
+ assert(ret == -EINVAL);
+
+ msrs->entries[0].data ^= 1;
+
+ /* Should be able to change a variable one. */
+ msrs->entries[msrs->nmsrs - 1].data ^= 1;
+ ret = kvm_vcpu_ioctl(env, KVM_SET_MSRS, msrs);
+ printf("KVM_SET_MSRS(nmsrs=%u,entries[%u]=changed) => %s\n",
+ msrs->nmsrs, msrs->nmsrs-1, strerror(-ret));
+ assert(ret == 0);
+
+ free(list);
+ free(msrs);
+}
+
int kvm_arch_init_vcpu(CPUARMState *env)
{
+ struct kvm_sregs sregs;
+ int ret;
+
+ sregs.target = KVM_ARM_TARGET_CORTEX_A15;
+ sregs.num_features = 0;
+
+ ret = kvm_vcpu_ioctl(env, KVM_SET_SREGS, &sregs);
+ if (ret == 0)
+ play_with_msrs(env);
return 0;
}
