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[34.140.115.198]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-487116c0c13sm81982145e9.7.2026.03.24.03.46.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2026 03:46:48 -0700 (PDT) Date: Tue, 24 Mar 2026 10:46:45 +0000 From: Vincent Donnefort To: Sebastian Ene Cc: alexandru.elisei@arm.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com, catalin.marinas@arm.com, dbrazdil@google.com, joey.gouly@arm.com, kees@kernel.org, mark.rutland@arm.com, maz@kernel.org, oupton@kernel.org, perlarsen@google.com, qperret@google.com, rananta@google.com, smostafa@google.com, suzuki.poulose@arm.com, tabba@google.com, tglx@kernel.org, bgrzesik@google.com, will@kernel.org, yuzenghui@huawei.com Subject: Re: [PATCH 02/14] KVM: arm64: Track host-unmapped MMIO regions in a static array Message-ID: References: <20260310124933.830025-1-sebastianene@google.com> <20260310124933.830025-3-sebastianene@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: <20260310124933.830025-3-sebastianene@google.com> On Tue, Mar 10, 2026 at 12:49:21PM +0000, Sebastian Ene wrote: > Introduce a registry to track protected MMIO regions that are unmapped > from the host stage-2 page tables. These regions are stored in a > fixed-size array and their ownership is donated to the hypervisor during > initialization to ensure host-exclusion and persistent tracking. > > Signed-off-by: Sebastian Ene > --- > arch/arm64/include/asm/kvm_pkvm.h | 10 ++++++++++ > arch/arm64/kvm/hyp/nvhe/mem_protect.c | 3 +++ > arch/arm64/kvm/hyp/nvhe/setup.c | 25 +++++++++++++++++++++++++ > 3 files changed, 38 insertions(+) > > diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h > index 757076ad4ec9..48ec7d519399 100644 > --- a/arch/arm64/include/asm/kvm_pkvm.h > +++ b/arch/arm64/include/asm/kvm_pkvm.h > @@ -17,6 +17,16 @@ > > #define HYP_MEMBLOCK_REGIONS 128 > > +#define PKVM_PROTECTED_REGS_NUM 8 > + > +struct pkvm_protected_reg { > + u64 start_pfn; > + size_t num_pages; nit: "u64 pfn, u64 nr_pages" to align with everywhere else. > +}; > + > +extern struct pkvm_protected_reg kvm_nvhe_sym(pkvm_protected_regs)[]; > +extern unsigned int kvm_nvhe_sym(num_protected_reg); > + > int pkvm_init_host_vm(struct kvm *kvm); > int pkvm_create_hyp_vm(struct kvm *kvm); > bool pkvm_hyp_vm_is_created(struct kvm *kvm); > diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c > index 0808367c52e5..7c125836b533 100644 > --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c > +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c > @@ -23,6 +23,9 @@ > > struct host_mmu host_mmu; > > +struct pkvm_protected_reg pkvm_protected_regs[PKVM_PROTECTED_REGS_NUM]; > +unsigned int num_protected_reg; > + > static struct hyp_pool host_s2_pool; > > static DEFINE_PER_CPU(struct pkvm_hyp_vm *, __current_vm); > diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c > index 90bd014e952f..ad5b96085e1b 100644 > --- a/arch/arm64/kvm/hyp/nvhe/setup.c > +++ b/arch/arm64/kvm/hyp/nvhe/setup.c > @@ -284,6 +284,27 @@ static int fix_hyp_pgtable_refcnt(void) > &walker); > } > > +static int unmap_protected_regions(void) > +{ > + struct pkvm_protected_reg *reg; > + int i, ret, j = 0; > + > + for (i = 0; i < num_protected_reg; i++) { > + reg = &pkvm_protected_regs[i]; > + for (j = 0; j < reg->num_pages; j++) { > + ret = __pkvm_host_donate_hyp_mmio(reg->start_pfn + j); If this is to make this static at boot, we don't even need __pkvm_host_donate_hyp_mmio() We can just map the region early enough in the hypervisor pkvm_create_mappings() in recreate_hyp_mappings() and then let fix_host_ownership() do the host stage2 unmapping. > + if (ret) > + goto err_setup; > + } > + } > + > + return 0; > +err_setup: > + for (j = j - 1; j >= 0; j--) > + __pkvm_hyp_donate_host_mmio(reg->start_pfn + j); > + return ret; > +} > + > void __noreturn __pkvm_init_finalise(void) > { > struct kvm_cpu_context *host_ctxt = host_data_ptr(host_ctxt); > @@ -324,6 +345,10 @@ void __noreturn __pkvm_init_finalise(void) > if (ret) > goto out; > > + ret = unmap_protected_regions(); > + if (ret) > + goto out; > + > ret = hyp_ffa_init(ffa_proxy_pages); > if (ret) > goto out; > -- > 2.53.0.473.g4a7958ca14-goog >