Re: [PATCH v12 04/10] hvf: Add Apple Silicon support

[Alexander Graf]

On 30.11.23 15:17, Philippe Mathieu-Daudé wrote:
> Hi,
>
> On 16/9/21 17:53, Alexander Graf wrote:
> > With Apple Silicon available to the masses, it's a good time to add 
> > support
> > for driving its virtualization extensions from QEMU.
> >
> > This patch adds all necessary architecture specific code to get basic 
> > VMs
> > working, including save/restore.
> >
> > Known limitations:
> >
> >    - WFI handling is missing (follows in later patch)
> >    - No watchpoint/breakpoint support
> >
> > Signed-off-by: Alexander Graf <agraf@csgraf.de>
> > Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
> > Reviewed-by: Sergio Lopez <slp@redhat.com>
> > Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
>
>
> > ---
> >   MAINTAINERS                 |   5 +
> >   accel/hvf/hvf-accel-ops.c   |   9 +
> >   include/sysemu/hvf_int.h    |  10 +-
> >   meson.build                 |   1 +
> >   target/arm/hvf/hvf.c        | 794 ++++++++++++++++++++++++++++++++++++
> >   target/arm/hvf/trace-events |  10 +
> >   target/i386/hvf/hvf.c       |   5 +
> >   7 files changed, 833 insertions(+), 1 deletion(-)
> >   create mode 100644 target/arm/hvf/hvf.c
> >   create mode 100644 target/arm/hvf/trace-events
>
>
> > +int hvf_arch_init_vcpu(CPUState *cpu)
> > +{
> > +    ARMCPU *arm_cpu = ARM_CPU(cpu);
> > +    CPUARMState *env = &arm_cpu->env;
> > +    uint32_t sregs_match_len = ARRAY_SIZE(hvf_sreg_match);
> > +    uint32_t sregs_cnt = 0;
> > +    uint64_t pfr;
> > +    hv_return_t ret;
> > +    int i;
> > +
> > +    env->aarch64 = 1;
> > +    asm volatile("mrs %0, cntfrq_el0" : "=r"(arm_cpu->gt_cntfrq_hz));
> > +
> > +    /* Allocate enough space for our sysreg sync */
> > +    arm_cpu->cpreg_indexes = g_renew(uint64_t, arm_cpu->cpreg_indexes,
> > +                                     sregs_match_len);
> > +    arm_cpu->cpreg_values = g_renew(uint64_t, arm_cpu->cpreg_values,
> > +                                    sregs_match_len);
> > +    arm_cpu->cpreg_vmstate_indexes = g_renew(uint64_t,
> > + arm_cpu->cpreg_vmstate_indexes,
> > +                                             sregs_match_len);
> > +    arm_cpu->cpreg_vmstate_values = g_renew(uint64_t,
> > + arm_cpu->cpreg_vmstate_values,
> > +                                            sregs_match_len);
> > +
> > +    memset(arm_cpu->cpreg_values, 0, sregs_match_len * 
> > sizeof(uint64_t));
> > +
> > +    /* Populate cp list for all known sysregs */
> > +    for (i = 0; i < sregs_match_len; i++) {
> > +        const ARMCPRegInfo *ri;
> > +        uint32_t key = hvf_sreg_match[i].key;
> > +
> > +        ri = get_arm_cp_reginfo(arm_cpu->cp_regs, key);
> > +        if (ri) {
> > +            assert(!(ri->type & ARM_CP_NO_RAW));
> > +            hvf_sreg_match[i].cp_idx = sregs_cnt;
> > +            arm_cpu->cpreg_indexes[sregs_cnt++] = cpreg_to_kvm_id(key);
>
> So this hash ...:
>
>     /*
>      * Convert a truncated 32 bit hashtable key into the full
>      * 64 bit KVM register ID.
>      */
>     static uint64_t cpreg_to_kvm_id(uint32_t cpregid)
>     {
>         uint64_t kvmid;
>
>         if (cpregid & CP_REG_AA64_MASK) {
>             kvmid = cpregid & ~CP_REG_AA64_MASK;
>             kvmid |= CP_REG_SIZE_U64 | CP_REG_ARM64;
>         } else {
>             kvmid = cpregid & ~(1 << 15);
>             if (cpregid & (1 << 15)) {
>                 kvmid |= CP_REG_SIZE_U64 | CP_REG_ARM;
>             } else {
>                 kvmid |= CP_REG_SIZE_U32 | CP_REG_ARM;
>             }
>         }
>         return kvmid;
>     }
>
> ... just happens to work the same way for HVF?


It never feeds into HVF - we only use these values as unique identifiers 
inside QEMU, no? See write_cpustate_to_list() and 
write_list_to_cpustate() for reference.


Alex