PMSIDR_EL1 is not part of the VCPU register context because the profiling control registers were not trapped and the register is read-only. With the introduction of the KVM_ARM_VCPU_SPE_STOP API, KVM will start trapping accesses to the profiling control registers, add PMSIDR_EL1 to the VCPU register context to prevent undefined exceptions in the guest.
Signed-off-by: Alexandru Elisei <[email protected]> --- arch/arm64/include/asm/kvm_host.h | 1 + arch/arm64/kvm/sys_regs.c | 22 +++++++++++++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index cc46f1406196..f866c4556ff9 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -247,6 +247,7 @@ enum vcpu_sysreg { PMSFCR_EL1, /* Sampling Filter Control Register */ PMSEVFR_EL1, /* Sampling Event Filter Register */ PMSLATFR_EL1, /* Sampling Latency Filter Register */ + PMSIDR_EL1, /* Sampling Profiling ID Register */ PMBLIMITR_EL1, /* Profiling Buffer Limit Address Register */ PMBPTR_EL1, /* Profiling Buffer Write Pointer Register */ PMBSR_EL1, /* Profiling Buffer Status/syndrome Register */ diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index cc711b081f31..1a85a0cedbec 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -603,6 +603,18 @@ static unsigned int spe_visibility(const struct kvm_vcpu *vcpu, return REG_HIDDEN; } +static void reset_pmsidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) +{ + /* + * When SPE is stopped by userspace, the guest reads the in-memory value + * of the register. When SPE is resumed, accesses to the control + * registers are not trapped and the guest reads the hardware + * value. Reset PMSIDR_EL1 to the hardware value to avoid mistmatches + * between the two. + */ + vcpu_write_sys_reg(vcpu, read_sysreg_s(SYS_PMSIDR_EL1), PMSIDR_EL1); +} + static bool access_spe_reg(struct kvm_vcpu *vcpu, struct sys_reg_params *p, const struct sys_reg_desc *r) { int reg = r->reg; @@ -613,10 +625,14 @@ static bool access_spe_reg(struct kvm_vcpu *vcpu, struct sys_reg_params *p, *vcpu_pc(vcpu), *vcpu_cpsr(vcpu)); } - if (p->is_write) + if (p->is_write) { + if (reg == PMSIDR_EL1) + return write_to_read_only(vcpu, p, r); + kvm_spe_write_sysreg(vcpu, reg, val); - else + } else { p->regval = kvm_spe_read_sysreg(vcpu, reg); + } return true; } @@ -1568,7 +1584,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { { SPE_SYS_REG(SYS_PMSFCR_EL1), .reg = PMSFCR_EL1 }, { SPE_SYS_REG(SYS_PMSEVFR_EL1), .reg = PMSEVFR_EL1 }, { SPE_SYS_REG(SYS_PMSLATFR_EL1), .reg = PMSLATFR_EL1 }, - { SPE_SYS_REG(SYS_PMSIDR_EL1), .reset = NULL }, + { SPE_SYS_REG(SYS_PMSIDR_EL1), .reset = reset_pmsidr, .reg = PMSIDR_EL1 }, { SPE_SYS_REG(SYS_PMBLIMITR_EL1), .reg = PMBLIMITR_EL1 }, { SPE_SYS_REG(SYS_PMBPTR_EL1), .reg = PMBPTR_EL1 }, { SPE_SYS_REG(SYS_PMBSR_EL1), .reg = PMBSR_EL1 }, -- 2.33.0 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
