linux-kernel - Re: [PATCH 06/15] KVM: x86/mmu: Remove need for a vcpu from mmu_try_to_unsync

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Date:   Thu, 18 Nov 2021 09:25:59 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Ben Gardon <bgardon@...gle.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Peter Xu <peterx@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Mingwei Zhang <mizhang@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>,
        Kai Huang <kai.huang@...el.com>,
        Keqian Zhu <zhukeqian1@...wei.com>,
        David Hildenbrand <david@...hat.com>
Subject: Re: [PATCH 06/15] KVM: x86/mmu: Remove need for a vcpu from
 mmu_try_to_unsync_pages

On 11/16/21 00:45, Ben Gardon wrote:
> The vCPU argument to mmu_try_to_unsync_pages is now only used to get a
> pointer to the associated struct kvm, so pass in the kvm pointer from
> the beginning to remove the need for a vCPU when calling the function.
> 
> 
> Signed-off-by: Ben Gardon <bgardon@...gle.com>
> ---
>   arch/x86/kvm/mmu/mmu.c          | 16 ++++++++--------
>   arch/x86/kvm/mmu/mmu_internal.h |  2 +-
>   arch/x86/kvm/mmu/spte.c         |  2 +-
>   3 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 7d0da79668c0..1e890509b93f 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -2561,10 +2561,10 @@ static int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
>   	return r;
>   }
>   
> -static void kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
> +static void kvm_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp)
>   {
>   	trace_kvm_mmu_unsync_page(sp);
> -	++vcpu->kvm->stat.mmu_unsync;
> +	++kvm->stat.mmu_unsync;
>   	sp->unsync = 1;
>   
>   	kvm_mmu_mark_parents_unsync(sp);
> @@ -2576,7 +2576,7 @@ static void kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
>    * were marked unsync (or if there is no shadow page), -EPERM if the SPTE must
>    * be write-protected.
>    */
> -int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
> +int mmu_try_to_unsync_pages(struct kvm *kvm, struct kvm_memory_slot *slot,
>   			    gfn_t gfn, bool can_unsync, bool prefetch)
>   {
>   	struct kvm_mmu_page *sp;
> @@ -2587,7 +2587,7 @@ int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
>   	 * track machinery is used to write-protect upper-level shadow pages,
>   	 * i.e. this guards the role.level == 4K assertion below!
>   	 */
> -	if (kvm_slot_page_track_is_active(vcpu->kvm, slot, gfn, KVM_PAGE_TRACK_WRITE))
> +	if (kvm_slot_page_track_is_active(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE))
>   		return -EPERM;
>   
>   	/*
> @@ -2596,7 +2596,7 @@ int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
>   	 * that case, KVM must complete emulation of the guest TLB flush before
>   	 * allowing shadow pages to become unsync (writable by the guest).
>   	 */
> -	for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) {
> +	for_each_gfn_indirect_valid_sp(kvm, sp, gfn) {
>   		if (!can_unsync)
>   			return -EPERM;
>   
> @@ -2615,7 +2615,7 @@ int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
>   		 */
>   		if (!locked) {
>   			locked = true;
> -			spin_lock(&vcpu->kvm->arch.mmu_unsync_pages_lock);
> +			spin_lock(&kvm->arch.mmu_unsync_pages_lock);
>   
>   			/*
>   			 * Recheck after taking the spinlock, a different vCPU
> @@ -2630,10 +2630,10 @@ int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
>   		}
>   
>   		WARN_ON(sp->role.level != PG_LEVEL_4K);
> -		kvm_unsync_page(vcpu, sp);
> +		kvm_unsync_page(kvm, sp);
>   	}
>   	if (locked)
> -		spin_unlock(&vcpu->kvm->arch.mmu_unsync_pages_lock);
> +		spin_unlock(&kvm->arch.mmu_unsync_pages_lock);
>   
>   	/*
>   	 * We need to ensure that the marking of unsync pages is visible
> diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
> index 52c6527b1a06..1073d10cce91 100644
> --- a/arch/x86/kvm/mmu/mmu_internal.h
> +++ b/arch/x86/kvm/mmu/mmu_internal.h
> @@ -118,7 +118,7 @@ static inline bool kvm_vcpu_ad_need_write_protect(struct kvm_vcpu *vcpu)
>   	       kvm_x86_ops.cpu_dirty_log_size;
>   }
>   
> -int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
> +int mmu_try_to_unsync_pages(struct kvm *kvm, struct kvm_memory_slot *slot,
>   			    gfn_t gfn, bool can_unsync, bool prefetch);
>   
>   void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
> diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
> index 75c666d3e7f1..b7271daa06c5 100644
> --- a/arch/x86/kvm/mmu/spte.c
> +++ b/arch/x86/kvm/mmu/spte.c
> @@ -160,7 +160,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
>   		 * e.g. it's write-tracked (upper-level SPs) or has one or more
>   		 * shadow pages and unsync'ing pages is not allowed.
>   		 */
> -		if (mmu_try_to_unsync_pages(vcpu, slot, gfn, can_unsync, prefetch)) {
> +		if (mmu_try_to_unsync_pages(vcpu->kvm, slot, gfn, can_unsync, prefetch)) {
>   			pgprintk("%s: found shadow page for %llx, marking ro\n",
>   				 __func__, gfn);
>   			wrprot = true;
> 

Queued, thanks.

Paolo