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Message-ID: <1537371052.9937.33.camel@intel.com>
Date: Wed, 19 Sep 2018 08:30:52 -0700
From: Sean Christopherson <sean.j.christopherson@...el.com>
To: Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>,
Jim Mattson <jmattson@...gle.com>,
Liran Alon <liran.alon@...cle.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 RESEND 6/9] x86/kvm/mmu: make space for source data
caching in struct kvm_mmu
On Tue, 2018-09-18 at 18:09 +0200, Vitaly Kuznetsov wrote:
> In preparation to MMU reconfiguration avoidance we need a space to
> cache source data. As this partially intersects with kvm_mmu_page_role,
> create 64bit sized union kvm_mmu_role holding both base_role and
> extended data. No functional change.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
> arch/x86/include/asm/kvm_host.h | 14 +++++++++++++-
> arch/x86/kvm/mmu.c | 19 ++++++++++++-------
> arch/x86/kvm/vmx.c | 2 +-
> 3 files changed, 26 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 527aaf45eba6..6ca7d28d57e9 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -273,6 +273,18 @@ union kvm_mmu_page_role {
> };
> };
>
> +union kvm_mmu_scache {
What about "kvm_mmu_extended_role" and a variable name of "ext"?
scache might be interpreted as "shadow cache", whereas I think you
intend "source cache". And it isn't immediately clear (to me) what
"source" refers to.
> + unsigned int word;
> +};
> +
> + unsigned long as_u64;
> + struct {
> + union kvm_mmu_page_role base_role;
Would it make sense to shorten this to simply "base"? The usage
looks like it's always deferenced in the context of kvm_mmu_role,
i.e. the "role" part appears to be redundant. And if scache were
renamed we'd end up with e.g. mmu_role.base and mmu_role.ext.
> + union kvm_mmu_scache scache;
> + };
> +};
> +
> struct kvm_rmap_head {
> unsigned long val;
> };
> @@ -360,7 +372,7 @@ struct kvm_mmu {
> void (*update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
> u64 *spte, const void *pte);
> hpa_t root_hpa;
> - union kvm_mmu_page_role base_role;
> + union kvm_mmu_role mmu_role;
> u8 root_level;
> u8 shadow_root_level;
> u8 ept_ad;
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 5f167823c50d..8d8e6fa75fa3 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2359,7 +2359,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
> int collisions = 0;
> LIST_HEAD(invalid_list);
>
> - role = vcpu->arch.mmu->base_role;
> + role = vcpu->arch.mmu->mmu_role.base_role;
> role.level = level;
> role.direct = direct;
> if (role.direct)
> @@ -4407,7 +4407,8 @@ static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu,
> void
> reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
> {
> - bool uses_nx = context->nx || context->base_role.smep_andnot_wp;
> + bool uses_nx = context->nx ||
> + context->mmu_role.base_role.smep_andnot_wp;
> struct rsvd_bits_validate *shadow_zero_check;
> int i;
>
> @@ -4726,7 +4727,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
> {
> struct kvm_mmu *context = vcpu->arch.mmu;
>
> - context->base_role.word = mmu_base_role_mask.word &
> + context->mmu_role.base_role.word = mmu_base_role_mask.word &
> kvm_calc_tdp_mmu_root_page_role(vcpu).word;
> context->page_fault = tdp_page_fault;
> context->sync_page = nonpaging_sync_page;
> @@ -4807,7 +4808,7 @@ void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu)
> else
> paging32_init_context(vcpu, context);
>
> - context->base_role.word = mmu_base_role_mask.word &
> + context->mmu_role.base_role.word = mmu_base_role_mask.word &
> kvm_calc_shadow_mmu_root_page_role(vcpu).word;
> reset_shadow_zero_bits_mask(vcpu, context);
> }
> @@ -4816,7 +4817,7 @@ EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu);
> static union kvm_mmu_page_role
> kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty)
> {
> - union kvm_mmu_page_role role = vcpu->arch.mmu->base_role;
> + union kvm_mmu_page_role role = vcpu->arch.mmu->mmu_role.base_role;
>
> role.level = PT64_ROOT_4LEVEL;
> role.direct = false;
> @@ -4846,7 +4847,8 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
> context->update_pte = ept_update_pte;
> context->root_level = PT64_ROOT_4LEVEL;
> context->direct_map = false;
> - context->base_role.word = root_page_role.word & mmu_base_role_mask.word;
> + context->mmu_role.base_role.word =
> + root_page_role.word & mmu_base_role_mask.word;
> context->get_pdptr = kvm_pdptr_read;
>
> update_permission_bitmask(vcpu, context, true);
> @@ -5161,10 +5163,13 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
>
> local_flush = true;
> while (npte--) {
> + unsigned int base_role =
> + vcpu->arch.mmu->mmu_role.base_role.word;
> +
> entry = *spte;
> mmu_page_zap_pte(vcpu->kvm, sp, spte);
> if (gentry &&
> - !((sp->role.word ^ vcpu->arch.mmu->base_role.word)
> + !((sp->role.word ^ base_role)
> & mmu_base_role_mask.word) && rmap_can_add(vcpu))
> mmu_pte_write_new_pte(vcpu, sp, spte, &gentry);
> if (need_remote_flush(entry, *spte))
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 29af40b9239f..79e0b0570dd1 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -9290,7 +9290,7 @@ static int nested_vmx_eptp_switching(struct kvm_vcpu *vcpu,
>
> kvm_mmu_unload(vcpu);
> mmu->ept_ad = accessed_dirty;
> - mmu->base_role.ad_disabled = !accessed_dirty;
> + mmu->mmu_role.base_role.ad_disabled = !accessed_dirty;
> vmcs12->ept_pointer = address;
> /*
> * TODO: Check what's the correct approach in case
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