Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sat, 13 Apr 2024 11:04:11 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH 2/4] KVM: arm64: maintain per VM value for CTR_EL0 |
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On Fri, 05 Apr 2024 13:01:06 +0100, Sebastian Ott <sebott@redhat.com> wrote: > > In preparation for CTR_EL0 emulation maintain a per VM for this > register and use it where appropriate. > > Signed-off-by: Sebastian Ott <sebott@redhat.com> > --- > arch/arm64/include/asm/kvm_host.h | 1 + > arch/arm64/kvm/sys_regs.c | 22 +++++++++++++++------- > 2 files changed, 16 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 9e8a496fb284..481216febb46 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -318,6 +318,7 @@ struct kvm_arch { > > /* PMCR_EL0.N value for the guest */ > u8 pmcr_n; > + u64 ctr_el0; > > /* Iterator for idreg debugfs */ > u8 idreg_debugfs_iter;
Please consider the alignment of the fields. This leaves a 7 byte hole that could be avoided (yes, I'm on a mission to reduce the size of the various structures, because they are absolute pigs).
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 131f5b0ca2b9..4d29b1a0842d 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -215,13 +215,21 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg) > /* CSSELR values; used to index KVM_REG_ARM_DEMUX_ID_CCSIDR */ > #define CSSELR_MAX 14 > > +static u64 kvm_get_ctr_el0(struct kvm *kvm) > +{ > + if (kvm->arch.ctr_el0) > + return kvm->arch.ctr_el0;
Is this relying on some bits not being 0?
> + > + return read_sanitised_ftr_reg(SYS_CTR_EL0);
Why isn't the shadow value always populated?
> +} > + > /* > * Returns the minimum line size for the selected cache, expressed as > * Log2(bytes). > */ > -static u8 get_min_cache_line_size(bool icache) > +static u8 get_min_cache_line_size(struct kvm *kvm, bool icache) > { > - u64 ctr = read_sanitised_ftr_reg(SYS_CTR_EL0); > + u64 ctr = kvm_get_ctr_el0(kvm); > u8 field; > > if (icache) > @@ -248,7 +256,7 @@ static u32 get_ccsidr(struct kvm_vcpu *vcpu, u32 csselr) > if (vcpu->arch.ccsidr) > return vcpu->arch.ccsidr[csselr]; > > - line_size = get_min_cache_line_size(csselr & CSSELR_EL1_InD); > + line_size = get_min_cache_line_size(vcpu->kvm, csselr & CSSELR_EL1_InD); > > /* > * Fabricate a CCSIDR value as the overriding value does not exist. > @@ -283,7 +291,7 @@ static int set_ccsidr(struct kvm_vcpu *vcpu, u32 csselr, u32 val) > u32 i; > > if ((val & CCSIDR_EL1_RES0) || > - line_size < get_min_cache_line_size(csselr & CSSELR_EL1_InD)) > + line_size < get_min_cache_line_size(vcpu->kvm, csselr & CSSELR_EL1_InD)) > return -EINVAL; > > if (!ccsidr) { > @@ -1862,7 +1870,7 @@ static bool access_ctr(struct kvm_vcpu *vcpu, struct sys_reg_params *p, > if (p->is_write) > return write_to_read_only(vcpu, p, r); > > - p->regval = read_sanitised_ftr_reg(SYS_CTR_EL0); > + p->regval = kvm_get_ctr_el0(vcpu->kvm); > return true; > } > > @@ -1882,7 +1890,7 @@ static bool access_clidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p, > */ > static u64 reset_clidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) > { > - u64 ctr_el0 = read_sanitised_ftr_reg(SYS_CTR_EL0); > + u64 ctr_el0 = kvm_get_ctr_el0(vcpu->kvm); > u64 clidr; > u8 loc; > > @@ -1935,7 +1943,7 @@ static u64 reset_clidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) > static int set_clidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, > u64 val) > { > - u64 ctr_el0 = read_sanitised_ftr_reg(SYS_CTR_EL0); > + u64 ctr_el0 = kvm_get_ctr_el0(vcpu->kvm); > u64 idc = !CLIDR_LOC(val) || (!CLIDR_LOUIS(val) && !CLIDR_LOUU(val)); > > if ((val & CLIDR_EL1_RES0) || (!(ctr_el0 & CTR_EL0_IDC) && idc))
Thanks,
M.
-- Without deviation from the norm, progress is not possible.
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