Re: [PATCH v4 6/6] target/riscv: select KVM AIA in riscv virt machine

[Daniel Henrique Barboza <dbarboza@ventanamicro.com>]

On 6/21/23 11:54, Yong-Xuan Wang wrote:
> Select KVM AIA when the host kernel has in-kernel AIA chip support.
> Since KVM AIA only has one APLIC instance, we map the QEMU APLIC
> devices to KVM APLIC.
> We also extend virt machine to specify the KVM AIA mode. The "kvm-aia"
> parameter is passed along with machine name in QEMU command-line.
> 1) "kvm-aia=emul": IMSIC is emulated by hypervisor
> 2) "kvm-aia=hwaccel": use hardware guest IMSIC
> 3) "kvm-aia=auto": use the hardware guest IMSICs whenever available
>                     otherwise we fallback to software emulation.
> 
> Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
> Reviewed-by: Jim Shu <jim.shu@sifive.com>
> ---

Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

>   hw/riscv/virt.c         | 92 ++++++++++++++++++++++++++++++++++-------
>   include/hw/riscv/virt.h |  1 +
>   2 files changed, 79 insertions(+), 14 deletions(-)
> 
> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> index 4a1d29a741..efa176a184 100644
> --- a/hw/riscv/virt.c
> +++ b/hw/riscv/virt.c
> @@ -35,6 +35,7 @@
>   #include "hw/riscv/virt.h"
>   #include "hw/riscv/boot.h"
>   #include "hw/riscv/numa.h"
> +#include "kvm_riscv.h"
>   #include "hw/intc/riscv_aclint.h"
>   #include "hw/intc/riscv_aplic.h"
>   #include "hw/intc/riscv_imsic.h"
> @@ -74,6 +75,12 @@
>   #error "Can't accomodate all IMSIC groups in address space"
>   #endif
>   
> +/* KVM AIA only supports APLIC.m. APLIC.w is always emulated by QEMU. */
> +static bool virt_use_kvm_aia(RISCVVirtState *s)
> +{
> +    return kvm_irqchip_in_kernel() && s->aia_type == VIRT_AIA_TYPE_APLIC_IMSIC;
> +}
> +
>   static const MemMapEntry virt_memmap[] = {
>       [VIRT_DEBUG] =        {        0x0,         0x100 },
>       [VIRT_MROM] =         {     0x1000,        0xf000 },
> @@ -642,7 +649,8 @@ static void create_fdt_socket_aplic(RISCVVirtState *s,
>                                       uint32_t msi_s_phandle,
>                                       uint32_t *phandle,
>                                       uint32_t *intc_phandles,
> -                                    uint32_t *aplic_phandles)
> +                                    uint32_t *aplic_phandles,
> +                                    int num_harts)
>   {
>       int cpu;
>       char *aplic_name;
> @@ -653,11 +661,11 @@ static void create_fdt_socket_aplic(RISCVVirtState *s,
>   
>       aplic_m_phandle = (*phandle)++;
>       aplic_s_phandle = (*phandle)++;
> -    aplic_cells = g_new0(uint32_t, s->soc[socket].num_harts * 2);
> +    aplic_cells = g_new0(uint32_t, num_harts * 2);
>   
>       if (!kvm_enabled()) {
>           /* M-level APLIC node */
> -        for (cpu = 0; cpu < s->soc[socket].num_harts; cpu++) {
> +        for (cpu = 0; cpu < num_harts; cpu++) {
>               aplic_cells[cpu * 2 + 0] = cpu_to_be32(intc_phandles[cpu]);
>               aplic_cells[cpu * 2 + 1] = cpu_to_be32(IRQ_M_EXT);
>           }
> @@ -691,7 +699,7 @@ static void create_fdt_socket_aplic(RISCVVirtState *s,
>       }
>   
>       /* S-level APLIC node */
> -    for (cpu = 0; cpu < s->soc[socket].num_harts; cpu++) {
> +    for (cpu = 0; cpu < num_harts; cpu++) {
>           aplic_cells[cpu * 2 + 0] = cpu_to_be32(intc_phandles[cpu]);
>           aplic_cells[cpu * 2 + 1] = cpu_to_be32(IRQ_S_EXT);
>       }
> @@ -798,17 +806,25 @@ static void create_fdt_sockets(RISCVVirtState *s, const MemMapEntry *memmap,
>           *msi_pcie_phandle = msi_s_phandle;
>       }
>   
> -    phandle_pos = ms->smp.cpus;
> -    for (socket = (socket_count - 1); socket >= 0; socket--) {
> -        phandle_pos -= s->soc[socket].num_harts;
> +    /* KVM AIA only has one APLIC instance */
> +    if (virt_use_kvm_aia(s)) {
> +        create_fdt_socket_aplic(s, memmap, 0,
> +            msi_m_phandle, msi_s_phandle, phandle,
> +            &intc_phandles[0], xplic_phandles, ms->smp.cpus);
> +    } else {
> +        phandle_pos = ms->smp.cpus;
> +        for (socket = (socket_count - 1); socket >= 0; socket--) {
> +            phandle_pos -= s->soc[socket].num_harts;
>   
> -        if (s->aia_type == VIRT_AIA_TYPE_NONE) {
> -            create_fdt_socket_plic(s, memmap, socket, phandle,
> -                &intc_phandles[phandle_pos], xplic_phandles);
> -        } else {
> -            create_fdt_socket_aplic(s, memmap, socket,
> -                msi_m_phandle, msi_s_phandle, phandle,
> -                &intc_phandles[phandle_pos], xplic_phandles);
> +            if (s->aia_type == VIRT_AIA_TYPE_NONE) {
> +                create_fdt_socket_plic(s, memmap, socket, phandle,
> +                    &intc_phandles[phandle_pos], xplic_phandles);
> +            } else {
> +                create_fdt_socket_aplic(s, memmap, socket,
> +                    msi_m_phandle, msi_s_phandle, phandle,
> +                    &intc_phandles[phandle_pos], xplic_phandles,
> +                    s->soc[socket].num_harts);
> +            }
>           }
>       }
>   
> @@ -819,6 +835,9 @@ static void create_fdt_sockets(RISCVVirtState *s, const MemMapEntry *memmap,
>               *irq_mmio_phandle = xplic_phandles[socket];
>               *irq_virtio_phandle = xplic_phandles[socket];
>               *irq_pcie_phandle = xplic_phandles[socket];
> +
> +            if (virt_use_kvm_aia(s))
> +                break;
>           }
>           if (socket == 1) {
>               *irq_virtio_phandle = xplic_phandles[socket];
> @@ -1454,6 +1473,14 @@ static void virt_machine_init(MachineState *machine)
>           }
>       }
>   
> +    if (virt_use_kvm_aia(s)) {
> +        kvm_riscv_aia_create(
> +            machine, s->kvm_aia_mode, IMSIC_MMIO_GROUP_MIN_SHIFT,
> +            VIRT_IRQCHIP_NUM_SOURCES, VIRT_IRQCHIP_NUM_MSIS,
> +            memmap[VIRT_APLIC_S].base, memmap[VIRT_IMSIC_S].base,
> +            s->aia_guests);
> +    }
> +
>       if (riscv_is_32bit(&s->soc[0])) {
>   #if HOST_LONG_BITS == 64
>           /* limit RAM size in a 32-bit system */
> @@ -1610,6 +1637,31 @@ static void virt_set_aia(Object *obj, const char *val, Error **errp)
>       }
>   }
>   
> +#if defined(CONFIG_KVM)
> +static char *virt_get_kvm_aia(Object *obj, Error **errp)
> +{
> +    RISCVVirtState *s = RISCV_VIRT_MACHINE(obj);
> +
> +    return kvm_aia_mode_str(s->kvm_aia_mode);
> +}
> +
> +static void virt_set_kvm_aia(Object *obj, const char *val, Error **errp)
> +{
> +    RISCVVirtState *s = RISCV_VIRT_MACHINE(obj);
> +
> +    if (!strcmp(val, "emul")) {
> +        s->kvm_aia_mode = KVM_DEV_RISCV_AIA_MODE_EMUL;
> +    } else if (!strcmp(val, "hwaccel")) {
> +        s->kvm_aia_mode = KVM_DEV_RISCV_AIA_MODE_HWACCEL;
> +    } else if (!strcmp(val, "auto")) {
> +        s->kvm_aia_mode = KVM_DEV_RISCV_AIA_MODE_AUTO;
> +    } else {
> +        error_setg(errp, "Invalid KVM AIA mode");
> +        error_append_hint(errp, "Valid values are emul, hwaccel, and auto.\n");
> +    }
> +}
> +#endif
> +
>   static bool virt_get_aclint(Object *obj, Error **errp)
>   {
>       RISCVVirtState *s = RISCV_VIRT_MACHINE(obj);
> @@ -1717,6 +1769,18 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
>       sprintf(str, "Set number of guest MMIO pages for AIA IMSIC. Valid value "
>                    "should be between 0 and %d.", VIRT_IRQCHIP_MAX_GUESTS);
>       object_class_property_set_description(oc, "aia-guests", str);
> +
> +#if defined(CONFIG_KVM)
> +    object_class_property_add_str(oc, "kvm-aia", virt_get_kvm_aia,
> +                                  virt_set_kvm_aia);
> +    object_class_property_set_description(oc, "kvm-aia",
> +                                          "Set KVM AIA mode. Valid values are "
> +                                          "emul, hwaccel, and auto. Default "
> +                                          "is auto.");
> +    object_property_set_default_str(object_class_property_find(oc, "kvm-aia"),
> +                                    "auto");
> +
> +#endif
>       object_class_property_add(oc, "acpi", "OnOffAuto",
>                                 virt_get_acpi, virt_set_acpi,
>                                 NULL, NULL);
> diff --git a/include/hw/riscv/virt.h b/include/hw/riscv/virt.h
> index e5c474b26e..d0140feeff 100644
> --- a/include/hw/riscv/virt.h
> +++ b/include/hw/riscv/virt.h
> @@ -56,6 +56,7 @@ struct RISCVVirtState {
>       bool have_aclint;
>       RISCVVirtAIAType aia_type;
>       int aia_guests;
> +    uint64_t kvm_aia_mode;
>       char *oem_id;
>       char *oem_table_id;
>       OnOffAuto acpi;