On 4/14/25 6:38 PM, Cornelia Huck wrote:
> From: Eric Auger <eric.au...@redhat.com>
>
> We want to give a chance to override the value of host ID regs.
> In a previous patch we made sure all their values could be fetched
> through kvm_get_one_reg() calls before their modification. After
> their potential modification we need to make sure we write back
nit: write their value back?
Eric
> the values through kvm_set_one_reg() calls.
>
> Make sure the cpreg_list is modified with updated values and
> transfer those values back to kvm.
>
> Signed-off-by: Eric Auger <eric.au...@redhat.com>
> Signed-off-by: Cornelia Huck <coh...@redhat.com>
> ---
> target/arm/kvm.c | 44 ++++++++++++++++++++++++++++++++++++++++-
> target/arm/trace-events | 1 +
> 2 files changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/target/arm/kvm.c b/target/arm/kvm.c
> index b07d5f16db50..9e4cca1705c8 100644
> --- a/target/arm/kvm.c
> +++ b/target/arm/kvm.c
> @@ -1083,6 +1083,39 @@ void kvm_arm_cpu_post_load(ARMCPU *cpu)
> }
> }
>
> +static void kvm_arm_writable_idregs_to_cpreg_list(ARMCPU *cpu)
> +{
> + if (!cpu->writable_map) {
> + return;
> + }
> + for (int i = 0; i < NR_ID_REGS; i++) {
> + uint64_t writable_mask = cpu->writable_map->regs[i];
> + uint64_t *cpreg;
> +
> + if (writable_mask) {
> + uint64_t previous, new;
> + int idx = kvm_idx_to_idregs_idx(i);
> + ARM64SysReg *sysregdesc;
> + uint32_t sysreg;
> +
> + if (idx == -1) {
> + /* sysreg writable, but we don't know it */
> + continue;
> + }
> + sysregdesc = &arm64_id_regs[idx];
> + sysreg = sysregdesc->sysreg;
> + cpreg = kvm_arm_get_cpreg_ptr(cpu,
> idregs_sysreg_to_kvm_reg(sysreg));
> + previous = *cpreg;
> + new = cpu->isar.idregs[idx];
> + if (previous != new) {
> + *cpreg = new;
> + trace_kvm_arm_writable_idregs_to_cpreg_list(sysregdesc->name,
> + previous, new);
> + }
> + }
> + }
> +}
> +
> void kvm_arm_reset_vcpu(ARMCPU *cpu)
> {
> int ret;
> @@ -2050,7 +2083,16 @@ int kvm_arch_init_vcpu(CPUState *cs)
> }
> cpu->mp_affinity = mpidr & ARM64_AFFINITY_MASK;
>
> - return kvm_arm_init_cpreg_list(cpu);
> + ret = kvm_arm_init_cpreg_list(cpu);
> + if (ret) {
> + return ret;
> + }
> + /* overwrite writable ID regs with their updated property values */
> + kvm_arm_writable_idregs_to_cpreg_list(cpu);
> +
> + write_list_to_kvmstate(cpu, 3);
> +
> + return 0;
> }
>
> int kvm_arch_destroy_vcpu(CPUState *cs)
> diff --git a/target/arm/trace-events b/target/arm/trace-events
> index 17e52c0705f2..955149ee1ac4 100644
> --- a/target/arm/trace-events
> +++ b/target/arm/trace-events
> @@ -14,3 +14,4 @@ arm_gt_update_irq(int timer, int irqstate) "gt_update_irq:
> timer %d irqstate %d"
> # kvm.c
> kvm_arm_fixup_msi_route(uint64_t iova, uint64_t gpa) "MSI iova = 0x%"PRIx64"
> is translated into 0x%"PRIx64
> get_host_cpu_idregs(const char *name, uint64_t value) "scratch vcpu host
> value for %s is 0x%"PRIx64
> +kvm_arm_writable_idregs_to_cpreg_list(const char *name, uint64_t previous,
> uint64_t new) "%s overwrite default 0x%"PRIx64" with 0x%"PRIx64
