2020-09-23 19:13:44

by Sean Christopherson

Subject: [PATCH] KVM: x86/mmu: Stash 'kvm' in a local variable in kvm_mmu_free_roots()

To make kvm_mmu_free_roots() a bit more readable, capture 'kvm' in a
local variable instead of doing vcpu->kvm over and over (and over).

No functional change intended.

Signed-off-by: Sean Christopherson <[email protected]>
---
arch/x86/kvm/mmu/mmu.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 76c5826e29a2..cdc498093450 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3603,6 +3603,7 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa,
void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
ulong roots_to_free)
{
+ struct kvm *kvm = vcpu->kvm;
int i;
LIST_HEAD(invalid_list);
bool free_active_root = roots_to_free & KVM_MMU_ROOT_CURRENT;
@@ -3620,22 +3621,21 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
return;
}

- spin_lock(&vcpu->kvm->mmu_lock);
+ spin_lock(&kvm->mmu_lock);

for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i))
- mmu_free_root_page(vcpu->kvm, &mmu->prev_roots[i].hpa,
+ mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa,
&invalid_list);

if (free_active_root) {
if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL &&
(mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) {
- mmu_free_root_page(vcpu->kvm, &mmu->root_hpa,
- &invalid_list);
+ mmu_free_root_page(kvm, &mmu->root_hpa, &invalid_list);
} else {
for (i = 0; i < 4; ++i)
if (mmu->pae_root[i] != 0)
- mmu_free_root_page(vcpu->kvm,
+ mmu_free_root_page(kvm,
&mmu->pae_root[i],
&invalid_list);
mmu->root_hpa = INVALID_PAGE;
@@ -3643,8 +3643,8 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
mmu->root_pgd = 0;
}

- kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
- spin_unlock(&vcpu->kvm->mmu_lock);
+ kvm_mmu_commit_zap_page(kvm, &invalid_list);
+ spin_unlock(&kvm->mmu_lock);
}
EXPORT_SYMBOL_GPL(kvm_mmu_free_roots);

--
2.28.0

2020-09-24 12:44:25

by Vitaly Kuznetsov

Subject: Re: [PATCH] KVM: x86/mmu: Stash 'kvm' in a local variable in kvm_mmu_free_roots()

Sean Christopherson <[email protected]> writes:

> To make kvm_mmu_free_roots() a bit more readable, capture 'kvm' in a
> local variable instead of doing vcpu->kvm over and over (and over).
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <[email protected]>
> ---
> arch/x86/kvm/mmu/mmu.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 76c5826e29a2..cdc498093450 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -3603,6 +3603,7 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa,
> void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> ulong roots_to_free)
> {
> + struct kvm *kvm = vcpu->kvm;
> int i;
> LIST_HEAD(invalid_list);
> bool free_active_root = roots_to_free & KVM_MMU_ROOT_CURRENT;
> @@ -3620,22 +3621,21 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> return;
> }
>
> - spin_lock(&vcpu->kvm->mmu_lock);
> + spin_lock(&kvm->mmu_lock);
>
> for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
> if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i))
> - mmu_free_root_page(vcpu->kvm, &mmu->prev_roots[i].hpa,
> + mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa,
> &invalid_list);
>
> if (free_active_root) {
> if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL &&
> (mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) {
> - mmu_free_root_page(vcpu->kvm, &mmu->root_hpa,
> - &invalid_list);
> + mmu_free_root_page(kvm, &mmu->root_hpa, &invalid_list);
> } else {
> for (i = 0; i < 4; ++i)
> if (mmu->pae_root[i] != 0)
> - mmu_free_root_page(vcpu->kvm,
> + mmu_free_root_page(kvm,
> &mmu->pae_root[i],
> &invalid_list);
> mmu->root_hpa = INVALID_PAGE;
> @@ -3643,8 +3643,8 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> mmu->root_pgd = 0;
> }
>
> - kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
> - spin_unlock(&vcpu->kvm->mmu_lock);
> + kvm_mmu_commit_zap_page(kvm, &invalid_list);
> + spin_unlock(&kvm->mmu_lock);
> }
> EXPORT_SYMBOL_GPL(kvm_mmu_free_roots);

What about kvm_mmu_get_page(), make_mmu_pages_available(),
mmu_alloc_root(), kvm_mmu_sync_roots(), direct_page_fault(),
kvm_mmu_pte_write() which seem to be using the same ugly pattern? :-)

Reviewed-by: Vitaly Kuznetsov <[email protected]>

--
Vitaly

2020-09-24 14:40:47

by Sean Christopherson

Subject: Re: [PATCH] KVM: x86/mmu: Stash 'kvm' in a local variable in kvm_mmu_free_roots()

On Thu, Sep 24, 2020 at 02:42:19PM +0200, Vitaly Kuznetsov wrote:
> What about kvm_mmu_get_page(), make_mmu_pages_available(),
> mmu_alloc_root(), kvm_mmu_sync_roots(), direct_page_fault(),
> kvm_mmu_pte_write() which seem to be using the same ugly pattern? :-)

Heh, good question. I guess only kvm_mmu_free_roots() managed to cross over
the threshold from "that's ugly" to "this is ridiculous".

2020-09-25 20:35:26

by Paolo Bonzini

Subject: Re: [PATCH] KVM: x86/mmu: Stash 'kvm' in a local variable in kvm_mmu_free_roots()

On 23/09/20 21:12, Sean Christopherson wrote:
> To make kvm_mmu_free_roots() a bit more readable, capture 'kvm' in a
> local variable instead of doing vcpu->kvm over and over (and over).
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <[email protected]>
> ---
> arch/x86/kvm/mmu/mmu.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 76c5826e29a2..cdc498093450 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -3603,6 +3603,7 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa,
> void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> ulong roots_to_free)
> {
> + struct kvm *kvm = vcpu->kvm;
> int i;
> LIST_HEAD(invalid_list);
> bool free_active_root = roots_to_free & KVM_MMU_ROOT_CURRENT;
> @@ -3620,22 +3621,21 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> return;
> }
>
> - spin_lock(&vcpu->kvm->mmu_lock);
> + spin_lock(&kvm->mmu_lock);
>
> for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
> if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i))
> - mmu_free_root_page(vcpu->kvm, &mmu->prev_roots[i].hpa,
> + mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa,
> &invalid_list);
>
> if (free_active_root) {
> if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL &&
> (mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) {
> - mmu_free_root_page(vcpu->kvm, &mmu->root_hpa,
> - &invalid_list);
> + mmu_free_root_page(kvm, &mmu->root_hpa, &invalid_list);
> } else {
> for (i = 0; i < 4; ++i)
> if (mmu->pae_root[i] != 0)
> - mmu_free_root_page(vcpu->kvm,
> + mmu_free_root_page(kvm,
> &mmu->pae_root[i],
> &invalid_list);
> mmu->root_hpa = INVALID_PAGE;
> @@ -3643,8 +3643,8 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> mmu->root_pgd = 0;
> }
>
> - kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
> - spin_unlock(&vcpu->kvm->mmu_lock);
> + kvm_mmu_commit_zap_page(kvm, &invalid_list);
> + spin_unlock(&kvm->mmu_lock);
> }
> EXPORT_SYMBOL_GPL(kvm_mmu_free_roots);
>
>

Queued this one, for now.

Paolo