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From: Atish Patra <atishp@atishpatra.org>
To: Anup Patel <apatel@ventanamicro.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Alistair Francis <Alistair.Francis@wdc.com>,
	Anup Patel <anup@brainfault.org>,
	KVM General <kvm@vger.kernel.org>,
	kvm-riscv@lists.infradead.org,
	linux-riscv <linux-riscv@lists.infradead.org>,
	"linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 5/7] RISC-V: KVM: Reduce KVM_MAX_VCPUS value
Date: Tue, 3 May 2022 19:15:20 -0700	[thread overview]
Message-ID: <CAOnJCU+yd7hqauHRYwnPqNKEgfy5FK06ezR64aH0Hm2AcNNadw@mail.gmail.com> (raw)
In-Reply-To: <20220420112450.155624-6-apatel@ventanamicro.com>

On Wed, Apr 20, 2022 at 4:25 AM Anup Patel <apatel@ventanamicro.com> wrote:
>
> Currently, the KVM_MAX_VCPUS value is 16384 for RV64 and 128
> for RV32.
>
> The KVM_MAX_VCPUS value is too high for RV64 and too low for
> RV32 compared to other architectures (e.g. x86 sets it to 1024
> and ARM64 sets it to 512). The too high value of KVM_MAX_VCPUS
> on RV64 also leads to VCPU mask on stack consuming 2KB.
>
> We set KVM_MAX_VCPUS to 1024 for both RV64 and RV32 to be
> aligned other architectures.
>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  arch/riscv/include/asm/kvm_host.h | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index 806f74dc0bfc..61d8b40e3d82 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -16,8 +16,7 @@
>  #include <asm/kvm_vcpu_fp.h>
>  #include <asm/kvm_vcpu_timer.h>
>
> -#define KVM_MAX_VCPUS                  \
> -       ((HGATP_VMID_MASK >> HGATP_VMID_SHIFT) + 1)
> +#define KVM_MAX_VCPUS                  1024
>
>  #define KVM_HALT_POLL_NS_DEFAULT       500000
>
> --
> 2.25.1
>

Reviewed-by: Atish Patra <atishp@rivosinc.com>

-- 
Regards,
Atish

  reply	other threads:[~2022-05-04  2:15 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-20 11:24 [PATCH v2 0/7] KVM RISC-V Sv57x4 support and HFENCE improvements Anup Patel
2022-04-20 11:24 ` [PATCH v2 1/7] RISC-V: KVM: Use G-stage name for hypervisor page table Anup Patel
2022-05-04  2:13   ` Atish Patra
2022-05-09  5:30     ` Anup Patel
2022-04-20 11:24 ` [PATCH v2 2/7] RISC-V: KVM: Add Sv57x4 mode support for G-stage Anup Patel
2022-05-04  2:14   ` Atish Patra
2022-05-09  5:31     ` Anup Patel
2022-04-20 11:24 ` [PATCH v2 3/7] RISC-V: KVM: Treat SBI HFENCE calls as NOPs Anup Patel
2022-05-04  2:14   ` Atish Patra
2022-05-09  5:32     ` Anup Patel
2022-04-20 11:24 ` [PATCH v2 4/7] RISC-V: KVM: Introduce range based local HFENCE functions Anup Patel
2022-05-06  6:49   ` Atish Patra
2022-05-09  5:33     ` Anup Patel
2022-04-20 11:24 ` [PATCH v2 5/7] RISC-V: KVM: Reduce KVM_MAX_VCPUS value Anup Patel
2022-05-04  2:15   ` Atish Patra [this message]
2022-05-09  5:33     ` Anup Patel
2022-04-20 11:24 ` [PATCH v2 6/7] RISC-V: KVM: Add remote HFENCE functions based on VCPU requests Anup Patel
2022-05-06  7:41   ` Atish Patra
2022-05-09  5:34     ` Anup Patel
2022-04-20 11:24 ` [PATCH v2 7/7] RISC-V: KVM: Cleanup stale TLB entries when host CPU changes Anup Patel
2022-05-06  7:53   ` Atish Patra
2022-05-09  5:34     ` Anup Patel

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