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Message-ID: <CAAhSdy1JPKwknR7HrNXkcBxL3QoVDAAzFthDS6nCocnzJor0XA@mail.gmail.com>
Date: Sun, 27 Nov 2022 18:07:17 +0530
From: Anup Patel <anup@...infault.org>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: Atish Patra <atishp@...shpatra.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org,
linux-riscv@...ts.infradead.org
Subject: Re: [PATCH] RISC-V: KVM: Simplify kvm_arch_prepare_memory_region()
On Sun, Nov 13, 2022 at 7:22 PM Christophe JAILLET
<christophe.jaillet@...adoo.fr> wrote:
>
> In kvm_arch_prepare_memory_region(), if no error occurs, a spin_lock()/
> spin_unlock() call can be avoided.
>
> Switch to kvm_riscv_gstage_iounmap() that is the same as the current code,
> but with a better semantic.
> It also embeds the locking logic. So it is avoided if ret == 0.
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Looks good to me.
Reviewed-by: Anup Patel <anup@...infault.org>
I have tested this on QEMU virt machine for RV64.
Queued this patch for Linux-6.2
Thanks,
Anup
> ---
> I don't use cross-compiler, so this patch is NOT even compile tested.
> ---
> arch/riscv/kvm/mmu.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index 3620ecac2fa1..c8834e463763 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -537,10 +537,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
> if (change == KVM_MR_FLAGS_ONLY)
> goto out;
>
> - spin_lock(&kvm->mmu_lock);
> if (ret)
> - gstage_unmap_range(kvm, base_gpa, size, false);
> - spin_unlock(&kvm->mmu_lock);
> + kvm_riscv_gstage_iounmap(kvm, base_gpa, size);
>
> out:
> mmap_read_unlock(current->mm);
> --
> 2.34.1
>
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