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Thu, 17 Jul 2025 09:04:47 -0700 (PDT) MIME-Version: 1.0 References: <20250522-pmu_event_info-v3-0-f7bba7fd9cfe@rivosinc.com> <20250522-pmu_event_info-v3-6-f7bba7fd9cfe@rivosinc.com> In-Reply-To: <20250522-pmu_event_info-v3-6-f7bba7fd9cfe@rivosinc.com> From: Anup Patel Date: Thu, 17 Jul 2025 21:34:36 +0530 X-Gm-Features: Ac12FXxSVTcSMonhmD8rqZBxMoPIHtsKSpNyakGFXvSyptDFl2Kq_s4PkOsoVXE Message-ID: Subject: Re: [PATCH v3 6/9] KVM: Add a helper function to validate vcpu gpa range To: Atish Patra Cc: Will Deacon , Mark Rutland , Paul Walmsley , Palmer Dabbelt , Mayuresh Chitale , linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Palmer Dabbelt , kvm@vger.kernel.org, kvm-riscv@lists.infradead.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250717_090450_258854_8F445C13 X-CRM114-Status: GOOD ( 21.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, May 23, 2025 at 12:33=E2=80=AFAM Atish Patra = wrote: > > The arch specific code may need to validate a gpa range if it is a shared > memory between the host and the guest. Currently, there are few places > where it is used in RISC-V implementation. Given the nature of the functi= on > it may be used for other architectures. Hence, a common helper function > is added. > > Signed-off-by: Atish Patra > --- > include/linux/kvm_host.h | 2 ++ > virt/kvm/kvm_main.c | 21 +++++++++++++++++++++ > 2 files changed, 23 insertions(+) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 291d49b9bf05..adda61cc4072 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1383,6 +1383,8 @@ static inline int kvm_vcpu_map_readonly(struct kvm_= vcpu *vcpu, gpa_t gpa, > > unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn); > unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn,= bool *writable); > +int kvm_vcpu_validate_gpa_range(struct kvm_vcpu *vcpu, gpa_t gpa, unsign= ed long len, > + bool write_access); > int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *dat= a, int offset, > int len); > int kvm_vcpu_read_guest_atomic(struct kvm_vcpu *vcpu, gpa_t gpa, void *d= ata, > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index e85b33a92624..3f52f5571fa6 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -3301,6 +3301,27 @@ int kvm_vcpu_write_guest(struct kvm_vcpu *vcpu, gp= a_t gpa, const void *data, > } > EXPORT_SYMBOL_GPL(kvm_vcpu_write_guest); > > +int kvm_vcpu_validate_gpa_range(struct kvm_vcpu *vcpu, gpa_t gpa, unsign= ed long len, > + bool write_access) > +{ > + gfn_t gfn =3D gpa >> PAGE_SHIFT; > + int seg; > + int offset =3D offset_in_page(gpa); > + bool writable =3D false; > + unsigned long hva; Nit: rearrange the variables in a inverted pyramid shape. > + > + while ((seg =3D next_segment(len, offset)) !=3D 0) { > + hva =3D kvm_vcpu_gfn_to_hva_prot(vcpu, gfn, &writable); > + if (kvm_is_error_hva(hva) || (writable ^ write_access)) > + return -EPERM; > + offset =3D 0; > + len -=3D seg; > + ++gfn; > + } > + return 0; > +} > +EXPORT_SYMBOL_GPL(kvm_vcpu_validate_gpa_range); > + > static int __kvm_gfn_to_hva_cache_init(struct kvm_memslots *slots, > struct gfn_to_hva_cache *ghc, > gpa_t gpa, unsigned long len) > > -- > 2.43.0 > Otherwise, looks good to me. Reviewed-by: Anup Patel Regards, Anup