[RFC PATCH v4 12/26] KVM: arm64: Make MVFR1_EL1 writable
From: Reiji Watanabe <hidden>
Date: 2022-01-06 04:34:20
Also in:
kvmarm, linux-arm-kernel
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
This patch adds id_reg_info for MVFR1_EL1 to make it writable by userspace. There are only a few valid combinations of values that can be set for FPHP and SIMDHP fields according to Arm ARM. Return an error when userspace tries to set those fields to values that don't match any of the valid combinations. Signed-off-by: Reiji Watanabe <redacted> --- arch/arm64/kvm/sys_regs.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 1707c7832593..1c18a19c5785 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c@@ -617,6 +617,36 @@ static int validate_id_dfr0_el1(struct kvm_vcpu *vcpu, return 0; } +static int validate_mvfr1_el1(struct kvm_vcpu *vcpu, + const struct id_reg_info *id_reg, u64 val) +{ + unsigned int fphp, simdhp; + struct fphp_simdhp { + unsigned int fphp; + unsigned int simdhp; + }; + /* Permitted fphp/simdhp value combinations according to Arm ARM */ + struct fphp_simdhp valid_fphp_simdhp[3] = {{0, 0}, {2, 1}, {3, 2}}; + int i; + bool is_valid_fphp_simdhp = false; + + fphp = cpuid_feature_extract_unsigned_field(val, MVFR1_FPHP_SHIFT); + simdhp = cpuid_feature_extract_unsigned_field(val, MVFR1_SIMDHP_SHIFT); + + for (i = 0; i < ARRAY_SIZE(valid_fphp_simdhp); i++) { + if (valid_fphp_simdhp[i].fphp == fphp && + valid_fphp_simdhp[i].simdhp == simdhp) { + is_valid_fphp_simdhp = true; + break; + } + } + + if (!is_valid_fphp_simdhp) + return -EINVAL; + + return 0; +} + static void init_id_aa64pfr0_el1_info(struct id_reg_info *id_reg) { u64 limit = id_reg->vcpu_limit_val;
@@ -774,6 +804,11 @@ static struct id_reg_info id_dfr0_el1_info = { .vcpu_mask = vcpu_mask_id_dfr0_el1, }; +static struct id_reg_info mvfr1_el1_info = { + .sys_reg = SYS_MVFR1_EL1, + .validate = validate_mvfr1_el1, +}; + /* * An ID register that needs special handling to control the value for the * guest must have its own id_reg_info in id_reg_info_table.
@@ -784,6 +819,7 @@ static struct id_reg_info id_dfr0_el1_info = { #define GET_ID_REG_INFO(id) (id_reg_info_table[IDREG_IDX(id)]) static struct id_reg_info *id_reg_info_table[KVM_ARM_ID_REG_MAX_NUM] = { [IDREG_IDX(SYS_ID_DFR0_EL1)] = &id_dfr0_el1_info, + [IDREG_IDX(SYS_MVFR1_EL1)] = &mvfr1_el1_info, [IDREG_IDX(SYS_ID_AA64PFR0_EL1)] = &id_aa64pfr0_el1_info, [IDREG_IDX(SYS_ID_AA64PFR1_EL1)] = &id_aa64pfr1_el1_info, [IDREG_IDX(SYS_ID_AA64DFR0_EL1)] = &id_aa64dfr0_el1_info,
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2.34.1.448.ga2b2bfdf31-goog