From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C439E4414; Wed, 7 May 2025 10:42:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746614555; cv=none; b=HviLTxEAm7o3XDV1Ad2uhqWT5+VAZhgt2wCBKTClAs/qf53Dv1pzdxPu2rsZW7/xqklNxRhKnFqG3eor8Nrxt30SAvzU1StLQmx+wvsFG/Or6/aOO7xK0joyZ592td7ZWRKq56YuWqUNlnuPbOaf0PxHAOcuKMzdkGyS6lpMwqo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746614555; c=relaxed/simple; bh=K7FRUYsKa68Pm5CEDV96iYy58lhLu7ZJV05L7Jo9o1c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=r5ebBKuPkFwMIUw4F0KjQe6vmTgqI71eTegaJ/DXcHMB1TuBrN3vCrbGS2wzvCS3I+Y5dM3SzZ3BMXTJRHMXTKO7VfKsntqREs0l+7cK2dnslMqT45XgLs6mB0vRRIqPgbsYSP9TsuuMRCItJvqzDU0OVq0GxE4aOOBdSolAl4s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0016B339; Wed, 7 May 2025 03:42:22 -0700 (PDT) Received: from [10.1.30.69] (unknown [10.1.30.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 04BF93F5A1; Wed, 7 May 2025 03:42:29 -0700 (PDT) Message-ID: <54a21b12-2b17-4e0a-9cbf-f68406fb003a@arm.com> Date: Wed, 7 May 2025 11:42:29 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 17/43] arm64: RME: Handle RMI_EXIT_RIPAS_CHANGE Content-Language: en-GB To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Gavin Shan , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" References: <20250416134208.383984-1-steven.price@arm.com> <20250416134208.383984-18-steven.price@arm.com> From: Suzuki K Poulose In-Reply-To: <20250416134208.383984-18-steven.price@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 16/04/2025 14:41, Steven Price wrote: > The guest can request that a region of it's protected address space is > switched between RIPAS_RAM and RIPAS_EMPTY (and back) using > RSI_IPA_STATE_SET. This causes a guest exit with the > RMI_EXIT_RIPAS_CHANGE code. We treat this as a request to convert a > protected region to unprotected (or back), exiting to the VMM to make > the necessary changes to the guest_memfd and memslot mappings. On the > next entry the RIPAS changes are committed by making RMI_RTT_SET_RIPAS > calls. > > The VMM may wish to reject the RIPAS change requested by the guest. For > now it can only do with by no longer scheduling the VCPU as we don't > currently have a usecase for returning that rejection to the guest, but > by postponing the RMI_RTT_SET_RIPAS changes to entry we leave the door > open for adding a new ioctl in the future for this purpose. > > Signed-off-by: Steven Price > --- > Changes since v7: > * Rework the loop in realm_set_ipa_state() to make it clear when the > 'next' output value of rmi_rtt_set_ripas() is used. > New patch for v7: The code was previously split awkwardly between two > other patches. > --- > arch/arm64/kvm/rme.c | 88 ++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 88 insertions(+) > > diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c > index bee9dfe12e03..fe0d5b8703d2 100644 > --- a/arch/arm64/kvm/rme.c > +++ b/arch/arm64/kvm/rme.c > @@ -624,6 +624,65 @@ void kvm_realm_unmap_range(struct kvm *kvm, unsigned long start, > realm_unmap_private_range(kvm, start, end); > } > > +static int realm_set_ipa_state(struct kvm_vcpu *vcpu, > + unsigned long start, > + unsigned long end, > + unsigned long ripas, > + unsigned long *top_ipa) > +{ > + struct kvm *kvm = vcpu->kvm; > + struct realm *realm = &kvm->arch.realm; > + struct realm_rec *rec = &vcpu->arch.rec; > + phys_addr_t rd_phys = virt_to_phys(realm->rd); > + phys_addr_t rec_phys = virt_to_phys(rec->rec_page); > + struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache; > + unsigned long ipa = start; > + int ret = 0; > + > + while (ipa < end) { > + unsigned long next; > + > + ret = rmi_rtt_set_ripas(rd_phys, rec_phys, ipa, end, &next); > + > + if (RMI_RETURN_STATUS(ret) == RMI_SUCCESS) { > + ipa = next; > + } else if (RMI_RETURN_STATUS(ret) == RMI_ERROR_RTT) { > + int walk_level = RMI_RETURN_INDEX(ret); > + int level = find_map_level(realm, ipa, end); > + > + /* > + * If the RMM walk ended early then more tables are > + * needed to reach the required depth to set the RIPAS. > + */ > + if (walk_level < level) { > + ret = realm_create_rtt_levels(realm, ipa, > + walk_level, > + level, > + memcache); > + /* Retry with RTTs created */ minor nit: Do we need to add a comment here, saying, we stop processing the request if we run out of RTT pages in this go and Realm could retry it. > + if (!ret) > + continue; > + } else { > + ret = -EINVAL; > + } > + > + break; > + } else { > + WARN(1, "Unexpected error in %s: %#x\n", __func__, > + ret); > + ret = -ENXIO; > + break; > + } minor nit: Following from Gavin's comment on another patch, could switch() make the above code more readable and remove the continue; ? switch (RMI_RETURN_STATUS(ret)) { case RMI_SUCCESS: ipa = next; break; case RMI_ERROR_RTT: { } break; default: WARN(..); ret = -ENXIO; goto out; } I am fine either way. > + } > + out: > + *top_ipa = ipa; > + > + if (ripas == RMI_EMPTY && ipa != start) > + realm_unmap_private_range(kvm, start, ipa); > + > + return ret; > +} > + > static int realm_init_ipa_state(struct realm *realm, > unsigned long ipa, > unsigned long end) > @@ -863,6 +922,32 @@ void kvm_destroy_realm(struct kvm *kvm) > kvm_free_stage2_pgd(&kvm->arch.mmu); > } > > +static void kvm_complete_ripas_change(struct kvm_vcpu *vcpu) > +{ > + struct kvm *kvm = vcpu->kvm; > + struct realm_rec *rec = &vcpu->arch.rec; > + unsigned long base = rec->run->exit.ripas_base; > + unsigned long top = rec->run->exit.ripas_top; > + unsigned long ripas = rec->run->exit.ripas_value; > + unsigned long top_ipa; > + int ret; > + > + do { > + kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_page_cache, > + kvm_mmu_cache_min_pages(vcpu->arch.hw_mmu)); > + write_lock(&kvm->mmu_lock); > + ret = realm_set_ipa_state(vcpu, base, top, ripas, &top_ipa); > + write_unlock(&kvm->mmu_lock); > + > + if (WARN_RATELIMIT(ret && ret != -ENOMEM, > + "Unable to satisfy RIPAS_CHANGE for %#lx - %#lx, ripas: %#lx\n", > + base, top, ripas)) > + break; > + > + base = top_ipa; > + } while (top_ipa < top); > +} > + Rest looks good to me. Suzuki