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arm/arm64: KVM: Add PSCI version selection API

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Although we've implemented PSCI 0.1, 0.2 and 1.0, we expose either 0.1
or 1.0 to a guest, defaulting to the latest version of the PSCI
implementation that is compatible with the requested version. This is
no different from doing a firmware upgrade on KVM.

But in order to give a chance to hypothetical badly implemented guests
that would have a fit by discovering something other than PSCI 0.2,
let's provide a new API that allows userspace to pick one particular
version of the API.

This is implemented as a new class of "firmware" registers, where
we expose the PSCI version. This allows the PSCI version to be
save/restored as part of a guest migration, and also set to
any supported version if the guest requires it.

Cc: stable@vger.kernel.org #4.16
Reviewed-by: Christoffer Dall <cdall@kernel.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier
2018-01-21 16:42:56 +00:00
parent bf9a41377d
commit 85bd0ba1ff
10 changed files with 156 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

60
virt/kvm/arm/psci.c
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@@ -18,6 +18,7 @@
#include <linux/arm-smccc.h>
#include <linux/preempt.h>
#include <linux/kvm_host.h>
#include <linux/uaccess.h>
#include <linux/wait.h>
#include <asm/cputype.h>
@@ -427,3 +428,62 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
smccc_set_retval(vcpu, val, 0, 0, 0);
return 1;
}
int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
{
return 1; /* PSCI version */
}
int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
{
if (put_user(KVM_REG_ARM_PSCI_VERSION, uindices))
return -EFAULT;
return 0;
}
int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
if (reg->id == KVM_REG_ARM_PSCI_VERSION) {
void __user *uaddr = (void __user *)(long)reg->addr;
u64 val;
val = kvm_psci_version(vcpu, vcpu->kvm);
if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
return -EFAULT;
return 0;
}
return -EINVAL;
}
int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
if (reg->id == KVM_REG_ARM_PSCI_VERSION) {
void __user *uaddr = (void __user *)(long)reg->addr;
bool wants_02;
u64 val;
if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
return -EFAULT;
wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);
switch (val) {
case KVM_ARM_PSCI_0_1:
if (wants_02)
return -EINVAL;
vcpu->kvm->arch.psci_version = val;
return 0;
case KVM_ARM_PSCI_0_2:
case KVM_ARM_PSCI_1_0:
if (!wants_02)
return -EINVAL;
vcpu->kvm->arch.psci_version = val;
return 0;
}
}
return -EINVAL;
}