Re: [PATCH kvmtool 10/21] hw/rtc: Refactor trap handlers

Alexandru Elisei
2021-02-12T11:58:07Z

Hi Andre,

On 12/10/20 2:28 PM, Andre Przywara wrote:
> With the planned retirement of the special ioport emulation code, we
> need to provide emulation functions compatible with the MMIO prototype.
>
> Merge the two different trap handlers into one function, checking for
> read/write and data/index register inside.
> Adjust the trap handlers to use that new function, and provide shims to
> implement the old ioport interface, for now.
>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
> hw/rtc.c | 70 ++++++++++++++++++++++++++++----------------------------
> 1 file changed, 35 insertions(+), 35 deletions(-)
>
> diff --git a/hw/rtc.c b/hw/rtc.c
> index 5483879f..664d4cb0 100644
> --- a/hw/rtc.c
> +++ b/hw/rtc.c
> @@ -42,11 +42,37 @@ static inline unsigned char bin2bcd(unsigned val)
> return ((val / 10) << 4) + val % 10;
> }
>
> -static bool cmos_ram_data_in(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> +static void cmos_ram_io(struct kvm_cpu *vcpu, u64 addr, u8 *data,
> + u32 len, u8 is_write, void *ptr)
> {
> struct tm *tm;
> time_t ti;
>
> + if (is_write) {
> + if (addr == 0x70) { /* index register */
> + u8 value = ioport__read8(data);
> +
> + vcpu->kvm->nmi_disabled = value & (1UL << 7);
> + rtc.cmos_idx = value & ~(1UL << 7);
> +
> + return;
> + }
> +
> + switch (rtc.cmos_idx) {
> + case RTC_REG_C:
> + case RTC_REG_D:
> + /* Read-only */
> + break;
> + default:
> + rtc.cmos_data[rtc.cmos_idx] = ioport__read8(data);
> + break;
> + }
> + return;
> + }
> +
> + if (addr == 0x70)
> + return;
> +
> time(&ti);
>
> tm = gmtime(&ti);
> @@ -92,42 +118,23 @@ static bool cmos_ram_data_in(struct ioport *ioport, struct kvm_cpu *vcpu, u16 po
> ioport__write8(data, rtc.cmos_data[rtc.cmos_idx]);
> break;
> }
> -
> - return true;
> }
>
> -static bool cmos_ram_data_out(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> +static bool cmos_ram_in(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> {
> - switch (rtc.cmos_idx) {
> - case RTC_REG_C:
> - case RTC_REG_D:
> - /* Read-only */
> - break;
> - default:
> - rtc.cmos_data[rtc.cmos_idx] = ioport__read8(data);
> - break;
> - }
> -
> + cmos_ram_io(vcpu, port, data, size, false, NULL);
> return true;
> }
>
> -static struct ioport_operations cmos_ram_data_ioport_ops = {
> - .io_out = cmos_ram_data_out,
> - .io_in = cmos_ram_data_in,
> -};
> -
> -static bool cmos_ram_index_out(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> +static bool cmos_ram_out(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void *data, int size)
> {
> - u8 value = ioport__read8(data);
> -
> - vcpu->kvm->nmi_disabled = value & (1UL << 7);
> - rtc.cmos_idx = value & ~(1UL << 7);
> -
> + cmos_ram_io(vcpu, port, data, size, true, NULL);
> return true;
> }
>
> -static struct ioport_operations cmos_ram_index_ioport_ops = {
> - .io_out = cmos_ram_index_out,
> +static struct ioport_operations cmos_ram_ioport_ops = {
> + .io_out = cmos_ram_out,
> + .io_in = cmos_ram_in,
> };
>
> #ifdef CONFIG_HAS_LIBFDT
> @@ -162,21 +169,15 @@ int rtc__init(struct kvm *kvm)
> return r;
>
> /* PORT 0070-007F - CMOS RAM/RTC (REAL TIME CLOCK) */
> - r = ioport__register(kvm, 0x0070, &cmos_ram_index_ioport_ops, 1, NULL);
> + r = ioport__register(kvm, 0x0070, &cmos_ram_ioport_ops, 2, NULL);
> if (r < 0)
> goto out_device;
>
> - r = ioport__register(kvm, 0x0071, &cmos_ram_data_ioport_ops, 1, NULL);
> - if (r < 0)
> - goto out_ioport;
> -
> /* Set the VRT bit in Register D to indicate valid RAM and time */
> rtc.cmos_data[RTC_REG_D] = RTC_REG_D_VRT;
>
> return r;
>
> -out_ioport:
> - ioport__unregister(kvm, 0x0070);
> out_device:
> device__unregister(&rtc_dev_hdr);
>
> @@ -188,7 +189,6 @@ int rtc__exit(struct kvm *kvm)
> {
> /* PORT 0070-007F - CMOS RAM/RTC (REAL TIME CLOCK) */
> ioport__unregister(kvm, 0x0070);
> - ioport__unregister(kvm, 0x0071);
>
> return 0;
> }

The behaviour is preserved with this patch, and it compiles, so:

Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>

Thanks,
Alex