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[34.90.134.61]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aa68f4eb962sm383187366b.3.2024.12.11.00.57.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Dec 2024 00:57:25 -0800 (PST) Date: Wed, 11 Dec 2024 08:57:22 +0000 From: Quentin Perret To: Fuad Tabba Cc: Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Vincent Donnefort , Sebastian Ene , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 12/18] KVM: arm64: Introduce __pkvm_host_relax_guest_perms() Message-ID: References: <20241203103735.2267589-1-qperret@google.com> <20241203103735.2267589-13-qperret@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tuesday 10 Dec 2024 at 14:56:05 (+0000), Fuad Tabba wrote: > Hi Quentin, > > On Tue, 3 Dec 2024 at 10:38, Quentin Perret wrote: > > > > Introduce a new hypercall allowing the host to relax the stage-2 > > permissions of mappings in a non-protected guest page-table. It will be > > used later once we start allowing RO memslots and dirty logging. > > > > Signed-off-by: Quentin Perret > > --- > > arch/arm64/include/asm/kvm_asm.h | 1 + > > arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 1 + > > arch/arm64/kvm/hyp/nvhe/hyp-main.c | 20 ++++++++++++++++ > > arch/arm64/kvm/hyp/nvhe/mem_protect.c | 23 +++++++++++++++++++ > > 4 files changed, 45 insertions(+) > > > > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h > > index 0b6c4d325134..5d51933e44fb 100644 > > --- a/arch/arm64/include/asm/kvm_asm.h > > +++ b/arch/arm64/include/asm/kvm_asm.h > > @@ -67,6 +67,7 @@ enum __kvm_host_smccc_func { > > __KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp, > > __KVM_HOST_SMCCC_FUNC___pkvm_host_share_guest, > > __KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_guest, > > + __KVM_HOST_SMCCC_FUNC___pkvm_host_relax_guest_perms, > > __KVM_HOST_SMCCC_FUNC___kvm_adjust_pc, > > __KVM_HOST_SMCCC_FUNC___kvm_vcpu_run, > > __KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context, > > diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h > > index e528a42ed60e..db0dd83c2457 100644 > > --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h > > +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h > > @@ -41,6 +41,7 @@ int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages); > > int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages); > > int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu, enum kvm_pgtable_prot prot); > > int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm); > > +int __pkvm_host_relax_guest_perms(u64 gfn, enum kvm_pgtable_prot prot, struct pkvm_hyp_vcpu *vcpu); > > The parameters are the same as __pkvm_host_share_guest, but in a > different order. I looked ahead at later patches in the series, and similar > issues regarding parameter type and ordering, so I won't mention it > for the later patches. Ack to this and the other comment below, thanks for the review! > > > bool addr_is_memory(phys_addr_t phys); > > int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot); > > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > > index 04a9053ae1d5..60dd56bbd743 100644 > > --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c > > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c > > @@ -267,6 +267,25 @@ static void handle___pkvm_host_unshare_guest(struct kvm_cpu_context *host_ctxt) > > cpu_reg(host_ctxt, 1) = ret; > > } > > > > +static void handle___pkvm_host_relax_guest_perms(struct kvm_cpu_context *host_ctxt) > > +{ > > + DECLARE_REG(u64, gfn, host_ctxt, 1); > > + DECLARE_REG(enum kvm_pgtable_prot, prot, host_ctxt, 2); > > + struct pkvm_hyp_vcpu *hyp_vcpu; > > + int ret = -EINVAL; > > + > > + if (!is_protected_kvm_enabled()) > > + goto out; > > + > > + hyp_vcpu = pkvm_get_loaded_hyp_vcpu(); > > + if (!hyp_vcpu || pkvm_hyp_vcpu_is_protected(hyp_vcpu)) > > + goto out; > > + > > + ret = __pkvm_host_relax_guest_perms(gfn, prot, hyp_vcpu); > > +out: > > + cpu_reg(host_ctxt, 1) = ret; > > +} > > + > > static void handle___kvm_adjust_pc(struct kvm_cpu_context *host_ctxt) > > { > > DECLARE_REG(struct kvm_vcpu *, vcpu, host_ctxt, 1); > > @@ -478,6 +497,7 @@ static const hcall_t host_hcall[] = { > > HANDLE_FUNC(__pkvm_host_unshare_hyp), > > HANDLE_FUNC(__pkvm_host_share_guest), > > HANDLE_FUNC(__pkvm_host_unshare_guest), > > + HANDLE_FUNC(__pkvm_host_relax_guest_perms), > > HANDLE_FUNC(__kvm_adjust_pc), > > HANDLE_FUNC(__kvm_vcpu_run), > > HANDLE_FUNC(__kvm_flush_vm_context), > > diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c > > index aa27a3e42e5e..d4b28e93e790 100644 > > --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c > > +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c > > @@ -1480,3 +1480,26 @@ int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm) > > > > return ret; > > } > > + > > +int __pkvm_host_relax_guest_perms(u64 gfn, enum kvm_pgtable_prot prot, struct pkvm_hyp_vcpu *vcpu) > > +{ > > + struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu); > > + u64 ipa = hyp_pfn_to_phys(gfn); > > + u64 phys; > > + int ret; > > + > > + if ((prot & KVM_PGTABLE_PROT_RWX) != prot) > > + return -EPERM; > > Why not > > + if (prot & ~KVM_PGTABLE_PROT_RWX) > > Simpler and consistent with similar checks in the file (e.g., > __pkvm_host_share_guest) > > Cheers, > /fuad > > > > + > > + host_lock_component(); > > + guest_lock_component(vm); > > + > > + ret = __check_host_unshare_guest(vm, &phys, ipa); > > + if (!ret) > > + ret = kvm_pgtable_stage2_relax_perms(&vm->pgt, ipa, prot, 0); > > + > > + guest_unlock_component(vm); > > + host_unlock_component(); > > + > > + return ret; > > +} > > -- > > 2.47.0.338.g60cca15819-goog > >