linux-kernel - [PATCH v2 5/7] RISC-V: KVM: Reduce KVM_MAX

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Date:   Wed, 20 Apr 2022 16:54:48 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Atish Patra <atishp@...shpatra.org>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Alistair Francis <Alistair.Francis@....com>,
        Anup Patel <anup@...infault.org>, kvm@...r.kernel.org,
        kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Anup Patel <apatel@...tanamicro.com>
Subject: [PATCH v2 5/7] RISC-V: KVM: Reduce KVM_MAX_VCPUS value

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@...tanamicro.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