Re: [PATCH v5 01/10] KVM: arm64: Factor out firmware register handling from psci.c

From: Raghavendra Rao Ananta
Date: Tue Apr 12 2022 - 12:42:17 EST

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In reply to: Gavin Shan: "Re: [PATCH v5 01/10] KVM: arm64: Factor out firmware register handling from psci.c"
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Hi Gavin,

On Tue, Apr 12, 2022 at 12:07 AM Gavin Shan <gshan@xxxxxxxxxx> wrote:
>
> Hi Raghavendra,
>
> On 4/7/22 9:15 AM, Raghavendra Rao Ananta wrote:
> > Common hypercall firmware register handing is currently employed
> > by psci.c. Since the upcoming patches add more of these registers,
> > it's better to move the generic handling to hypercall.c for a
> > cleaner presentation.
> >
> > While we are at it, collect all the firmware registers under
> > fw_reg_ids[] to help implement kvm_arm_get_fw_num_regs() and
> > kvm_arm_copy_fw_reg_indices() in a generic way. Also, define
> > KVM_REG_FEATURE_LEVEL_MASK using a GENMASK instead.
> >
> > No functional change intended.
> >
> > Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> > Reviewed-by: Oliver Upton <oupton@xxxxxxxxxx>
> > ---
> > arch/arm64/kvm/guest.c | 2 +-
> > arch/arm64/kvm/hypercalls.c | 185 +++++++++++++++++++++++++++++++++++
> > arch/arm64/kvm/psci.c | 183 ----------------------------------
> > include/kvm/arm_hypercalls.h | 7 ++
> > include/kvm/arm_psci.h | 7 --
> > 5 files changed, 193 insertions(+), 191 deletions(-)
> >
>
> Apart from the below nits:
>
> Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>
>
> > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> > index 7e15b03fbdf8..0d5cca56cbda 100644
> > --- a/arch/arm64/kvm/guest.c
> > +++ b/arch/arm64/kvm/guest.c
> > @@ -18,7 +18,7 @@
> > #include <linux/string.h>
> > #include <linux/vmalloc.h>
> > #include <linux/fs.h>
> > -#include <kvm/arm_psci.h>
> > +#include <kvm/arm_hypercalls.h>
> > #include <asm/cputype.h>
> > #include <linux/uaccess.h>
> > #include <asm/fpsimd.h>
> > diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
> > index 202b8c455724..fa6d9378d8e7 100644
> > --- a/arch/arm64/kvm/hypercalls.c
> > +++ b/arch/arm64/kvm/hypercalls.c
> > @@ -158,3 +158,188 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
> > smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
> > return 1;
> > }
> > +
> > +static const u64 kvm_arm_fw_reg_ids[] = {
> > + KVM_REG_ARM_PSCI_VERSION,
> > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
> > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
> > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
> > +};
> > +
> > +int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
> > +{
> > + return ARRAY_SIZE(kvm_arm_fw_reg_ids);
> > +}
> > +
> > +int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < ARRAY_SIZE(kvm_arm_fw_reg_ids); i++) {
> > + if (put_user(kvm_arm_fw_reg_ids[i], uindices++))
> > + return -EFAULT;
> > + }
> > +
> > + return 0;
> > +}
> > +
>
> Since we're here, I think we can make this function to return 'ARRAY_SIZE(kvm_arm_fw_reg_ids)',
> to be consistent with copy_{core, sve}_reg_indices(). With the return value fixed, additional
> patch can use @ret in kvm_arm_copy_reg_indices().
>
Well we can, however, since this is mostly refactoring, I didn't want
to change the original functionality of the code.
The only caller of this is kvm_arm_copy_reg_indices()
(arch/arm64/kvm/guest.c), which only checks for 'ret < 0'.
Also, do you have a need for it? If yes, I can change it in the next revision.

> > +#define KVM_REG_FEATURE_LEVEL_WIDTH 4
> > +#define KVM_REG_FEATURE_LEVEL_MASK GENMASK(KVM_REG_FEATURE_LEVEL_WIDTH, 0)
> > +
>
> It seems 'BIT()' is replaced with 'GENMASK' in the movement, but it's not mentioned
> in the commit log. I guess it'd better to mention it if you agree.
>
The last sentence of the commit text mentions this :)
Please let me know if it's not clear.

> > +/*
> > + * Convert the workaround level into an easy-to-compare number, where higher
> > + * values mean better protection.
> > + */
> > +static int get_kernel_wa_level(u64 regid)
> > +{
> > + switch (regid) {
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
> > + switch (arm64_get_spectre_v2_state()) {
> > + case SPECTRE_VULNERABLE:
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
> > + case SPECTRE_MITIGATED:
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL;
> > + case SPECTRE_UNAFFECTED:
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED;
> > + }
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
> > + switch (arm64_get_spectre_v4_state()) {
> > + case SPECTRE_MITIGATED:
> > + /*
> > + * As for the hypercall discovery, we pretend we
> > + * don't have any FW mitigation if SSBS is there at
> > + * all times.
> > + */
> > + if (cpus_have_final_cap(ARM64_SSBS))
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
> > + fallthrough;
> > + case SPECTRE_UNAFFECTED:
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
> > + case SPECTRE_VULNERABLE:
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
> > + }
> > + break;
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
> > + switch (arm64_get_spectre_bhb_state()) {
> > + case SPECTRE_VULNERABLE:
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
> > + case SPECTRE_MITIGATED:
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_AVAIL;
> > + case SPECTRE_UNAFFECTED:
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_REQUIRED;
> > + }
> > + return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
> > + }
> > +
> > + return -EINVAL;
> > +}
> > +
> > +int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> > +{
> > + void __user *uaddr = (void __user *)(long)reg->addr;
> > + u64 val;
> > +
> > + switch (reg->id) {
> > + case KVM_REG_ARM_PSCI_VERSION:
> > + val = kvm_psci_version(vcpu);
> > + break;
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
> > + val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
> > + break;
> > + default:
> > + return -ENOENT;
> > + }
> > +
> > + if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
> > + return -EFAULT;
> > +
> > + return 0;
> > +}
> > +
> > +int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> > +{
> > + void __user *uaddr = (void __user *)(long)reg->addr;
> > + u64 val;
> > + int wa_level;
> > +
> > + if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
> > + return -EFAULT;
> > +
> > + switch (reg->id) {
> > + case KVM_REG_ARM_PSCI_VERSION:
> > + {
> > + bool wants_02;
> > +
> > + 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:
> > + case KVM_ARM_PSCI_1_1:
> > + if (!wants_02)
> > + return -EINVAL;
> > + vcpu->kvm->arch.psci_version = val;
> > + return 0;
> > + }
> > + break;
> > + }
> > +
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
> > + if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
> > + return -EINVAL;
> > +
> > + if (get_kernel_wa_level(reg->id) < val)
> > + return -EINVAL;
> > +
> > + return 0;
> > +
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
> > + if (val & ~(KVM_REG_FEATURE_LEVEL_MASK |
> > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
> > + return -EINVAL;
> > +
> > + /* The enabled bit must not be set unless the level is AVAIL. */
> > + if ((val & KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED) &&
> > + (val & KVM_REG_FEATURE_LEVEL_MASK) != KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL)
> > + return -EINVAL;
> > +
> > + /*
> > + * Map all the possible incoming states to the only two we
> > + * really want to deal with.
> > + */
> > + switch (val & KVM_REG_FEATURE_LEVEL_MASK) {
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL:
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN:
> > + wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
> > + break;
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
> > + case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
> > + wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
> > + break;
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + /*
> > + * We can deal with NOT_AVAIL on NOT_REQUIRED, but not the
> > + * other way around.
> > + */
> > + if (get_kernel_wa_level(reg->id) < wa_level)
> > + return -EINVAL;
> > +
> > + return 0;
> > + default:
> > + return -ENOENT;
> > + }
> > +
> > + return -EINVAL;
> > +}
> > diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
> > index 372da09a2fab..bdfa93ca57d1 100644
> > --- a/arch/arm64/kvm/psci.c
> > +++ b/arch/arm64/kvm/psci.c
> > @@ -439,186 +439,3 @@ int kvm_psci_call(struct kvm_vcpu *vcpu)
> > return -EINVAL;
> > }
> > }
> > -
> > -int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
> > -{
> > - return 4; /* PSCI version and three workaround registers */
> > -}
> > -
> > -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;
> > -
> > - if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1, uindices++))
> > - return -EFAULT;
> > -
> > - if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2, uindices++))
> > - return -EFAULT;
> > -
> > - if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3, uindices++))
> > - return -EFAULT;
> > -
> > - return 0;
> > -}
> > -
> > -#define KVM_REG_FEATURE_LEVEL_WIDTH 4
> > -#define KVM_REG_FEATURE_LEVEL_MASK (BIT(KVM_REG_FEATURE_LEVEL_WIDTH) - 1)
> > -
> > -/*
> > - * Convert the workaround level into an easy-to-compare number, where higher
> > - * values mean better protection.
> > - */
> > -static int get_kernel_wa_level(u64 regid)
> > -{
> > - switch (regid) {
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
> > - switch (arm64_get_spectre_v2_state()) {
> > - case SPECTRE_VULNERABLE:
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
> > - case SPECTRE_MITIGATED:
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL;
> > - case SPECTRE_UNAFFECTED:
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED;
> > - }
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
> > - switch (arm64_get_spectre_v4_state()) {
> > - case SPECTRE_MITIGATED:
> > - /*
> > - * As for the hypercall discovery, we pretend we
> > - * don't have any FW mitigation if SSBS is there at
> > - * all times.
> > - */
> > - if (cpus_have_final_cap(ARM64_SSBS))
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
> > - fallthrough;
> > - case SPECTRE_UNAFFECTED:
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
> > - case SPECTRE_VULNERABLE:
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
> > - }
> > - break;
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
> > - switch (arm64_get_spectre_bhb_state()) {
> > - case SPECTRE_VULNERABLE:
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
> > - case SPECTRE_MITIGATED:
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_AVAIL;
> > - case SPECTRE_UNAFFECTED:
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_REQUIRED;
> > - }
> > - return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
> > - }
> > -
> > - return -EINVAL;
> > -}
> > -
> > -int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> > -{
> > - void __user *uaddr = (void __user *)(long)reg->addr;
> > - u64 val;
> > -
> > - switch (reg->id) {
> > - case KVM_REG_ARM_PSCI_VERSION:
> > - val = kvm_psci_version(vcpu);
> > - break;
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
> > - val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
> > - break;
> > - default:
> > - return -ENOENT;
> > - }
> > -
> > - if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
> > - return -EFAULT;
> > -
> > - return 0;
> > -}
> > -
> > -int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> > -{
> > - void __user *uaddr = (void __user *)(long)reg->addr;
> > - u64 val;
> > - int wa_level;
> > -
> > - if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
> > - return -EFAULT;
> > -
> > - switch (reg->id) {
> > - case KVM_REG_ARM_PSCI_VERSION:
> > - {
> > - bool wants_02;
> > -
> > - 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:
> > - case KVM_ARM_PSCI_1_1:
> > - if (!wants_02)
> > - return -EINVAL;
> > - vcpu->kvm->arch.psci_version = val;
> > - return 0;
> > - }
> > - break;
> > - }
> > -
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
> > - if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
> > - return -EINVAL;
> > -
> > - if (get_kernel_wa_level(reg->id) < val)
> > - return -EINVAL;
> > -
> > - return 0;
> > -
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
> > - if (val & ~(KVM_REG_FEATURE_LEVEL_MASK |
> > - KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
> > - return -EINVAL;
> > -
> > - /* The enabled bit must not be set unless the level is AVAIL. */
> > - if ((val & KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED) &&
> > - (val & KVM_REG_FEATURE_LEVEL_MASK) != KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL)
> > - return -EINVAL;
> > -
> > - /*
> > - * Map all the possible incoming states to the only two we
> > - * really want to deal with.
> > - */
> > - switch (val & KVM_REG_FEATURE_LEVEL_MASK) {
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL:
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN:
> > - wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
> > - break;
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
> > - case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
> > - wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
> > - break;
> > - default:
> > - return -EINVAL;
> > - }
> > -
> > - /*
> > - * We can deal with NOT_AVAIL on NOT_REQUIRED, but not the
> > - * other way around.
> > - */
> > - if (get_kernel_wa_level(reg->id) < wa_level)
> > - return -EINVAL;
> > -
> > - return 0;
> > - default:
> > - return -ENOENT;
> > - }
> > -
> > - return -EINVAL;
> > -}
> > diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
> > index 0e2509d27910..5d38628a8d04 100644
> > --- a/include/kvm/arm_hypercalls.h
> > +++ b/include/kvm/arm_hypercalls.h
> > @@ -40,4 +40,11 @@ static inline void smccc_set_retval(struct kvm_vcpu *vcpu,
> > vcpu_set_reg(vcpu, 3, a3);
> > }
> >
> > +struct kvm_one_reg;
> > +
> > +int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu);
> > +int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
> > +int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
> > +int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
> > +
> > #endif
> > diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
> > index 68b96c3826c3..6e55b9283789 100644
> > --- a/include/kvm/arm_psci.h
> > +++ b/include/kvm/arm_psci.h
> > @@ -39,11 +39,4 @@ static inline int kvm_psci_version(struct kvm_vcpu *vcpu)
> >
> > int kvm_psci_call(struct kvm_vcpu *vcpu);
> >
> > -struct kvm_one_reg;
> > -
> > -int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu);
> > -int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
> > -int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
> > -int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
> > -
> > #endif /* __KVM_ARM_PSCI_H__ */
> >
>
> Thanks,
> Gavin
Thank you for the review, Gavin.

Regards,
Raghavendra
>

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In reply to: Gavin Shan: "Re: [PATCH v5 01/10] KVM: arm64: Factor out firmware register handling from psci.c"
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