Re: [PATCH v5 5/5] target/riscv: select KVM AIA in riscv virt machine

[Andrew Jones]

On Thu, Jul 13, 2023 at 08:43:57AM +0000, 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         | 125 ++++++++++++++++++++++++++++++----------
>  include/hw/riscv/virt.h |   1 +
>  2 files changed, 97 insertions(+), 29 deletions(-)
> 
> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> index 26b3aff28e..b74142d978 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"
> @@ -75,6 +76,12 @@
>  #error "Can't accomodate all IMSIC groups in address space"
>  #endif
>  
> +/* KVM AIA only supports APLIC MSI. APLIC Wired 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 },
> @@ -609,16 +616,16 @@ static void create_fdt_one_aplic(RISCVVirtState *s, int 
> socket,
>                                   uint32_t *intc_phandles,
>                                   uint32_t aplic_phandle,
>                                   uint32_t aplic_child_phandle,
> -                                 bool m_mode)
> +                                 bool m_mode, int num_harts)
>  {
>      int cpu;
>      char *aplic_name;
>      uint32_t *aplic_cells;
>      MachineState *ms = MACHINE(s);
>  
> -    aplic_cells = g_new0(uint32_t, s->soc[socket].num_harts * 2);
> +    aplic_cells = g_new0(uint32_t, num_harts * 2);
>  
> -    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(m_mode ? IRQ_M_EXT : 
> IRQ_S_EXT);
>      }
> @@ -632,7 +639,7 @@ static void create_fdt_one_aplic(RISCVVirtState *s, int 
> socket,
>  
>      if (s->aia_type == VIRT_AIA_TYPE_APLIC) {
>          qemu_fdt_setprop(ms->fdt, aplic_name, "interrupts-extended",
> -            aplic_cells, s->soc[socket].num_harts * sizeof(uint32_t) * 2);
> +            aplic_cells, num_harts * sizeof(uint32_t) * 2);
>      } else {
>          qemu_fdt_setprop_cell(ms->fdt, aplic_name, "msi-parent", 
> msi_phandle);
>      }
> @@ -662,7 +669,8 @@ 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)
>  {
>      char *aplic_name;
>      unsigned long aplic_addr;
> @@ -679,7 +687,7 @@ static void create_fdt_socket_aplic(RISCVVirtState *s,
>          create_fdt_one_aplic(s, socket, aplic_addr, 
> memmap[VIRT_APLIC_M].size,
>                               msi_m_phandle, intc_phandles,
>                               aplic_m_phandle, aplic_s_phandle,
> -                             true);
> +                             true, num_harts);
>      }
>  
>      /* S-level APLIC node */
> @@ -688,7 +696,7 @@ static void create_fdt_socket_aplic(RISCVVirtState *s,
>      create_fdt_one_aplic(s, socket, aplic_addr, memmap[VIRT_APLIC_S].size,
>                           msi_s_phandle, intc_phandles,
>                           aplic_s_phandle, 0,
> -                         false);
> +                         false, num_harts);
>  
>      aplic_name = g_strdup_printf("/soc/aplic@%lx", aplic_addr);
>  
> @@ -772,34 +780,48 @@ 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);
> +            }
>          }
>      }
>  
>      g_free(intc_phandles);
>  
> -    for (socket = 0; socket < socket_count; socket++) {
> -        if (socket == 0) {
> -            *irq_mmio_phandle = xplic_phandles[socket];
> -            *irq_virtio_phandle = xplic_phandles[socket];
> -            *irq_pcie_phandle = xplic_phandles[socket];
> -        }
> -        if (socket == 1) {
> -            *irq_virtio_phandle = xplic_phandles[socket];
> -            *irq_pcie_phandle = xplic_phandles[socket];
> -        }
> -        if (socket == 2) {
> -            *irq_pcie_phandle = xplic_phandles[socket];
> +    if (virt_use_kvm_aia(s)) {
> +        *irq_mmio_phandle = xplic_phandles[0];
> +        *irq_virtio_phandle = xplic_phandles[0];
> +        *irq_pcie_phandle = xplic_phandles[0];
> +    } else {
> +        for (socket = 0; socket < socket_count; socket++) {
> +            if (socket == 0) {
> +                *irq_mmio_phandle = xplic_phandles[socket];
> +                *irq_virtio_phandle = xplic_phandles[socket];
> +                *irq_pcie_phandle = xplic_phandles[socket];
> +            }
> +            if (socket == 1) {
> +                *irq_virtio_phandle = xplic_phandles[socket];
> +                *irq_pcie_phandle = xplic_phandles[socket];
> +            }
> +            if (socket == 2) {
> +                *irq_pcie_phandle = xplic_phandles[socket];
> +            }
>          }
>      }
>  
> @@ -1430,6 +1452,14 @@ 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 */
> @@ -1575,6 +1605,31 @@ 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 g_strdup(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);
> @@ -1685,6 +1740,18 @@ 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;
> -- 
> 2.17.1
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>