Hi Andrew,
On Tue, 09 Mar 2021 18:59:39 +0000,
Andrew Jones <drjo...@redhat.com> wrote:
>
> The virt machine already checks KVM_CAP_ARM_VM_IPA_SIZE to get the
> upper bound of the IPA size. If that bound is lower than the highest
> possible GPA for the machine, then QEMU will error out. However, the
> IPA is set to 40 when the highest GPA is less than or equal to 40,
> even when KVM may only support an IPA limit as low as 32. This means
> KVM may fail the VM creation unnecessarily. Additionally, 40 is
> selected with the value 0, which means use the default, and that gets
> around a check in some versions of KVM, causing a difficult to debug
> fail. Always use the IPA size that corresponds to the highest possible
> GPA, unless it's lower than 32, in which case use 32.
>
> Signed-off-by: Andrew Jones <drjo...@redhat.com>
> ---
> hw/arm/virt.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 371147f3ae9c..7bf563715b4e 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -2547,14 +2547,13 @@ static int virt_kvm_type(MachineState *ms, const char
> *type_str)
> "require an IPA range (%d bits) larger than "
> "the one supported by the host (%d bits)",
> requested_pa_size, max_vm_pa_size);
> - exit(1);
> + exit(1);
> }
> +
> /*
> - * By default we return 0 which corresponds to an implicit legacy
> - * 40b IPA setting. Otherwise we return the actual requested PA
> - * logsize
> + * KVM requires the IPA size to be at least 32 bits.
> */
> - return requested_pa_size > 40 ? requested_pa_size : 0;
> + return requested_pa_size < 32 ? 32 : requested_pa_size;
Doesn't this break on older kernels (pre 233a7cb23531, which is
anything up 4.19), where the 'type' parameter passed at VM creation
time was expected to be 0 and nothing else?
I had a quick go at qemu a couple of weeks back and came up with the
following hack, but never actually tested it (there is no way qemu can
fit in the initramfs I am feeding to this damn machine...).
Thanks,
M.
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 371147f3ae..3301bb8dba 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2534,8 +2534,11 @@ static HotplugHandler
*virt_machine_get_hotplug_handler(MachineState *machine,
static int virt_kvm_type(MachineState *ms, const char *type_str)
{
VirtMachineState *vms = VIRT_MACHINE(ms);
- int max_vm_pa_size = kvm_arm_get_max_vm_ipa_size(ms);
+ int max_vm_pa_size;
int requested_pa_size;
+ bool fixed_ipa;
+
+ max_vm_pa_size = kvm_arm_get_max_vm_ipa_size(ms, &fixed_ipa);
/* we freeze the memory map to compute the highest gpa */
virt_set_memmap(vms);
@@ -2550,11 +2553,12 @@ static int virt_kvm_type(MachineState *ms, const char
*type_str)
exit(1);
}
/*
- * By default we return 0 which corresponds to an implicit legacy
- * 40b IPA setting. Otherwise we return the actual requested PA
- * logsize
+ * We return the requested PA log size, unless KVM only supports
+ * the implicit legacy 40b IPA setting, in which case we return 0.
*/
- return requested_pa_size > 40 ? requested_pa_size : 0;
+ if (fixed_ipa)
+ return 0;
+ return requested_pa_size;
}
static void virt_machine_class_init(ObjectClass *oc, void *data)
diff --git a/slirp b/slirp
index 8f43a99191..ce94eba204 160000
--- a/slirp
+++ b/slirp
@@ -1 +1 @@
-Subproject commit 8f43a99191afb47ca3f3c6972f6306209f367ece
+Subproject commit ce94eba2042d52a0ba3d9e252ebce86715e94275
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 00e124c812..5f576730e6 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -230,12 +230,14 @@ bool kvm_arm_pmu_supported(void)
return kvm_check_extension(kvm_state, KVM_CAP_ARM_PMU_V3);
}
-int kvm_arm_get_max_vm_ipa_size(MachineState *ms)
+int kvm_arm_get_max_vm_ipa_size(MachineState *ms, bool *fixed_ipa)
{
KVMState *s = KVM_STATE(ms->accelerator);
int ret;
ret = kvm_check_extension(s, KVM_CAP_ARM_VM_IPA_SIZE);
+ *fixed_ipa = !(ret > 0);
+
return ret > 0 ? ret : 40;
}
diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index eb81b7059e..75d7133a35 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -311,10 +311,11 @@ bool kvm_arm_sve_supported(void);
/**
* kvm_arm_get_max_vm_ipa_size:
* @ms: Machine state handle
+ * @fixed_ipa: Indicate whether the IPA address space is a fixed value
*
* Returns the number of bits in the IPA address space supported by KVM
*/
-int kvm_arm_get_max_vm_ipa_size(MachineState *ms);
+int kvm_arm_get_max_vm_ipa_size(MachineState *ms, bool *fixed_ipa);
/**
* kvm_arm_sync_mpstate_to_kvm:
@@ -409,7 +410,7 @@ static inline void kvm_arm_add_vcpu_properties(Object *obj)
g_assert_not_reached();
}
-static inline int kvm_arm_get_max_vm_ipa_size(MachineState *ms)
+static inline int kvm_arm_get_max_vm_ipa_size(MachineState *ms, bool
*fixed_ipa)
{
g_assert_not_reached();
}
--
Without deviation from the norm, progress is not possible.
