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[2003:f6:af03:d200:6e0f:c0b9:21f9:db5c]) by smtp.gmail.com with ESMTPSA id p11-20020a05640243cb00b0049e19136c22sm3627509edc.95.2023.01.18.06.48.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Jan 2023 06:48:50 -0800 (PST) From: Mathias Krause To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sean Christopherson , Paolo Bonzini , Mathias Krause Subject: [PATCH v2 1/3] KVM: x86/mmu: avoid indirect call for get_cr3 Date: Wed, 18 Jan 2023 15:50:28 +0100 Message-Id: <20230118145030.40845-2-minipli@grsecurity.net> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230118145030.40845-1-minipli@grsecurity.net> References: <20230118145030.40845-1-minipli@grsecurity.net> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Paolo Bonzini Most of the time, calls to get_guest_pgd result in calling kvm_read_cr3 (the exception is only nested TDP). Hardcode the default instead of using the get_cr3 function, avoiding a retpoline if they are enabled. Signed-off-by: Paolo Bonzini Signed-off-by: Mathias Krause --- arch/x86/kvm/mmu/mmu.c | 31 ++++++++++++++++++++----------- arch/x86/kvm/mmu/paging_tmpl.h | 2 +- 2 files changed, 21 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index aeb240b339f5..505768631614 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -241,6 +241,20 @@ static struct kvm_mmu_role_regs vcpu_to_role_regs(stru= ct kvm_vcpu *vcpu) return regs; } =20 +static unsigned long get_guest_cr3(struct kvm_vcpu *vcpu) +{ + return kvm_read_cr3(vcpu); +} + +static inline unsigned long kvm_mmu_get_guest_pgd(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) +{ + if (IS_ENABLED(CONFIG_RETPOLINE) && mmu->get_guest_pgd =3D=3D get_guest_c= r3) + return kvm_read_cr3(vcpu); + + return mmu->get_guest_pgd(vcpu); +} + static inline bool kvm_available_flush_tlb_with_range(void) { return kvm_x86_ops.tlb_remote_flush_with_range; @@ -3722,7 +3736,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vc= pu) int quadrant, i, r; hpa_t root; =20 - root_pgd =3D mmu->get_guest_pgd(vcpu); + root_pgd =3D kvm_mmu_get_guest_pgd(vcpu, mmu); root_gfn =3D root_pgd >> PAGE_SHIFT; =20 if (mmu_check_root(vcpu, root_gfn)) @@ -4172,7 +4186,7 @@ static bool kvm_arch_setup_async_pf(struct kvm_vcpu *= vcpu, gpa_t cr2_or_gpa, arch.token =3D alloc_apf_token(vcpu); arch.gfn =3D gfn; arch.direct_map =3D vcpu->arch.mmu->root_role.direct; - arch.cr3 =3D vcpu->arch.mmu->get_guest_pgd(vcpu); + arch.cr3 =3D kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu); =20 return kvm_setup_async_pf(vcpu, cr2_or_gpa, kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch); @@ -4191,7 +4205,7 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu,= struct kvm_async_pf *work) return; =20 if (!vcpu->arch.mmu->root_role.direct && - work->arch.cr3 !=3D vcpu->arch.mmu->get_guest_pgd(vcpu)) + work->arch.cr3 !=3D kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu)) return; =20 kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true); @@ -4592,11 +4606,6 @@ void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t ne= w_pgd) } EXPORT_SYMBOL_GPL(kvm_mmu_new_pgd); =20 -static unsigned long get_cr3(struct kvm_vcpu *vcpu) -{ - return kvm_read_cr3(vcpu); -} - static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, unsigned int access) { @@ -5147,7 +5156,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu, context->page_fault =3D kvm_tdp_page_fault; context->sync_page =3D nonpaging_sync_page; context->invlpg =3D NULL; - context->get_guest_pgd =3D get_cr3; + context->get_guest_pgd =3D get_guest_cr3; context->get_pdptr =3D kvm_pdptr_read; context->inject_page_fault =3D kvm_inject_page_fault; =20 @@ -5297,7 +5306,7 @@ static void init_kvm_softmmu(struct kvm_vcpu *vcpu, =20 kvm_init_shadow_mmu(vcpu, cpu_role); =20 - context->get_guest_pgd =3D get_cr3; + context->get_guest_pgd =3D get_guest_cr3; context->get_pdptr =3D kvm_pdptr_read; context->inject_page_fault =3D kvm_inject_page_fault; } @@ -5311,7 +5320,7 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu, return; =20 g_context->cpu_role.as_u64 =3D new_mode.as_u64; - g_context->get_guest_pgd =3D get_cr3; + g_context->get_guest_pgd =3D get_guest_cr3; g_context->get_pdptr =3D kvm_pdptr_read; g_context->inject_page_fault =3D kvm_inject_page_fault; =20 diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index e5662dbd519c..78448fb84bd6 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -324,7 +324,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker= *walker, trace_kvm_mmu_pagetable_walk(addr, access); retry_walk: walker->level =3D mmu->cpu_role.base.level; - pte =3D mmu->get_guest_pgd(vcpu); + pte =3D kvm_mmu_get_guest_pgd(vcpu, mmu); have_ad =3D PT_HAVE_ACCESSED_DIRTY(mmu); =20 #if PTTYPE =3D=3D 64 --=20 2.39.0