linux-kernel - Re: [PATCH v2 15/18] KVM: arm64: Introduce __pkvm_host_mkyoung

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CA+EHjTzOjwNyUkS5_zSUiAbiCauLKKgkKU6TM_-+Wsh9A0FdRQ@mail.gmail.com>
Date: Tue, 10 Dec 2024 15:14:03 +0000
From: Fuad Tabba <tabba@...gle.com>
To: Quentin Perret <qperret@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Vincent Donnefort <vdonnefort@...gle.com>, 
	Sebastian Ene <sebastianene@...gle.com>, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 15/18] KVM: arm64: Introduce __pkvm_host_mkyoung_guest()

Hi Quentin,

On Tue, 3 Dec 2024 at 10:38, Quentin Perret <qperret@...gle.com> wrote:
>
> Plumb the kvm_pgtable_stage2_mkyoung() callback into pKVM for
> non-protected guests. It will be called later from the fault handling
> path.
>
> Signed-off-by: Quentin Perret <qperret@...gle.com>
> ---
>  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            | 19 ++++++++++++++++++
>  arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 20 +++++++++++++++++++
>  4 files changed, 41 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index cb676017d591..6178e12a0dbc 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -70,6 +70,7 @@ enum __kvm_host_smccc_func {
>         __KVM_HOST_SMCCC_FUNC___pkvm_host_relax_guest_perms,
>         __KVM_HOST_SMCCC_FUNC___pkvm_host_wrprotect_guest,
>         __KVM_HOST_SMCCC_FUNC___pkvm_host_test_clear_young_guest,
> +       __KVM_HOST_SMCCC_FUNC___pkvm_host_mkyoung_guest,
>         __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 554ce31882e6..3ae0c3ecff48 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> @@ -44,6 +44,7 @@ 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);
>  int __pkvm_host_wrprotect_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm);
>  int __pkvm_host_test_clear_young_guest(u64 gfn, bool mkold, struct pkvm_hyp_vm *vm);
> +int __pkvm_host_mkyoung_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu);
>
>  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 67cb6e284180..de0012a75827 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> @@ -333,6 +333,24 @@ static void handle___pkvm_host_test_clear_young_guest(struct kvm_cpu_context *ho
>         cpu_reg(host_ctxt, 1) = ret;
>  }
>
> +static void handle___pkvm_host_mkyoung_guest(struct kvm_cpu_context *host_ctxt)
> +{
> +       DECLARE_REG(u64, gfn, host_ctxt, 1);
> +       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_mkyoung_guest(gfn, 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);
> @@ -547,6 +565,7 @@ static const hcall_t host_hcall[] = {
>         HANDLE_FUNC(__pkvm_host_relax_guest_perms),
>         HANDLE_FUNC(__pkvm_host_wrprotect_guest),
>         HANDLE_FUNC(__pkvm_host_test_clear_young_guest),
> +       HANDLE_FUNC(__pkvm_host_mkyoung_guest),
>         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 0e064a7ed7c4..7605bd7f80b5 100644
> --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> @@ -1541,3 +1541,23 @@ int __pkvm_host_test_clear_young_guest(u64 gfn, bool mkold, struct pkvm_hyp_vm *
>
>         return ret;
>  }
> +
> +int __pkvm_host_mkyoung_guest(u64 gfn, 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;
> +
> +       host_lock_component();
> +       guest_lock_component(vm);
> +
> +       ret = __check_host_unshare_guest(vm, &phys, ipa);

While I'm bikeshedding some more, does the name
__check_host_unshare_guest() make sense? Should it be something like
__check_host_changeperm_guest(), or something along those lines? (feel
free to ignore this :) )

Thanks,
/fuad

> +       if (!ret)
> +               kvm_pgtable_stage2_mkyoung(&vm->pgt, ipa, 0);
> +
> +       guest_unlock_component(vm);
> +       host_unlock_component();
> +
> +       return ret;
> +}
> --
> 2.47.0.338.g60cca15819-goog
>