Re: [PATCH v2 1/2] hw/riscv/virt.c: fix non-KVM --enable-debug build

[Andrew Jones]

On Wed, Aug 30, 2023 at 10:35:02AM -0300, Daniel Henrique Barboza wrote:
> A build with --enable-debug and without KVM will fail as follows:
> 
> /usr/bin/ld: libqemu-riscv64-softmmu.fa.p/hw_riscv_virt.c.o: in function 
> `virt_machine_init':
> ./qemu/build/../hw/riscv/virt.c:1465: undefined reference to 
> `kvm_riscv_aia_create'
> 
> This happens because the code block with "if virt_use_kvm_aia(s)" isn't
> being ignored by the debug build, resulting in an undefined reference to
> a KVM only function.
> 
> Add a 'kvm_enabled()' conditional together with virt_use_kvm_aia() will
> make the compiler crop the kvm_riscv_aia_create() call entirely from a
> non-KVM build. Note that adding the 'kvm_enabled()' conditional inside
> virt_use_kvm_aia() won't fix the build because this function would need
> to be inlined multiple times to make the compiler zero out the entire
> block.
> 
> While we're at it, use kvm_enabled() in all instances where
> virt_use_kvm_aia() is checked to allow the compiler to elide these other
> kvm-only instances as well.
> 
> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
> Fixes: dbdb99948e ("target/riscv: select KVM AIA in riscv virt machine")
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  hw/riscv/virt.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> index 388e52a294..3b259b9305 100644
> --- a/hw/riscv/virt.c
> +++ b/hw/riscv/virt.c
> @@ -782,7 +782,7 @@ static void create_fdt_sockets(RISCVVirtState *s, const 
> MemMapEntry *memmap,
>      }
>  
>      /* KVM AIA only has one APLIC instance */
> -    if (virt_use_kvm_aia(s)) {
> +    if (kvm_enabled() && virt_use_kvm_aia(s)) {
>          create_fdt_socket_aplic(s, memmap, 0,
>                                  msi_m_phandle, msi_s_phandle, phandle,
>                                  &intc_phandles[0], xplic_phandles,
> @@ -808,7 +808,7 @@ static void create_fdt_sockets(RISCVVirtState *s, const 
> MemMapEntry *memmap,
>  
>      g_free(intc_phandles);
>  
> -    if (virt_use_kvm_aia(s)) {
> +    if (kvm_enabled() && virt_use_kvm_aia(s)) {
>          *irq_mmio_phandle = xplic_phandles[0];
>          *irq_virtio_phandle = xplic_phandles[0];
>          *irq_pcie_phandle = xplic_phandles[0];
> @@ -1461,7 +1461,7 @@ static void virt_machine_init(MachineState *machine)
>          }
>      }
>  
> -    if (virt_use_kvm_aia(s)) {
> +    if (kvm_enabled() && virt_use_kvm_aia(s)) {
>          kvm_riscv_aia_create(machine, IMSIC_MMIO_GROUP_MIN_SHIFT,
>                               VIRT_IRQCHIP_NUM_SOURCES, VIRT_IRQCHIP_NUM_MSIS,
>                               memmap[VIRT_APLIC_S].base,
> -- 
> 2.41.0
> 
>

I think I'd prefer

 /* We need this inlined for debug (-O0) builds */
 static inline QEMU_ALWAYS_INLINE bool virt_use_kvm_aia(RISCVVirtState *s)
 {
    return kvm_enabled() && kvm_irqchip_in_kernel() && s->aia_type == 
VIRT_AIA_TYPE_APLIC_IMSIC;
 }

assuming that works.

Either way,

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

Thanks,
drew