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 3067920C03C; Mon, 7 Apr 2025 16:35:22 +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=1744043725; cv=none; b=MQE+vIdFzuzY9HirjOouhE4DITmsENd70dQ6j2Su4lezksvKjYJR014+ODd7VwUYOlIZdO4GO185ab0vR5ChZdeC6o9PoyVoWdklYXAtJ8JopC1pAKNJcxorbzdSkI4LudHiN9mSY+stZbxiQ1yS9dLCznaYCK+PS8dyz2qWUsg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744043725; c=relaxed/simple; bh=LNnD2bDITRNhLIrHQbKqo/V3F9P9CZyDllsCX405OgA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=azWD6p0aVp9yzExjhSWDdE2vFLybjcymmtdG8vWd+fJE9FgwIjEFDaybtybS9TJQshFNnxH5OkOvGHF/km1fvr+SONQZ0IbTBnRiHvDMeRysMtiWjk33jhG2ZEdYwblRyE04nga+h3gl68enxNokxtq1nC6kXOpRFWx0S5QTqDg= 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 A6174106F; Mon, 7 Apr 2025 09:35:23 -0700 (PDT) Received: from [10.57.17.31] (unknown [10.57.17.31]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4D9893F694; Mon, 7 Apr 2025 09:35:18 -0700 (PDT) Message-ID: Date: Mon, 7 Apr 2025 17:35:16 +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 v7 35/45] arm64: RME: Propagate number of breakpoints and watchpoints to userspace To: Gavin Shan , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Jean-Philippe Brucker , Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , 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 , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" References: <20250213161426.102987-1-steven.price@arm.com> <20250213161426.102987-36-steven.price@arm.com> From: Steven Price Content-Language: en-GB In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 04/03/2025 23:45, Gavin Shan wrote: > On 2/14/25 2:14 AM, Steven Price wrote: >> From: Jean-Philippe Brucker >> >> The RMM describes the maximum number of BPs/WPs available to the guest >> in the Feature Register 0. Propagate those numbers into ID_AA64DFR0_EL1, >> which is visible to userspace. A VMM needs this information in order to >> set up realm parameters. >> >> Signed-off-by: Jean-Philippe Brucker >> Signed-off-by: Steven Price >> --- >>   arch/arm64/include/asm/kvm_rme.h |  2 ++ >>   arch/arm64/kvm/rme.c             | 22 ++++++++++++++++++++++ >>   arch/arm64/kvm/sys_regs.c        |  2 +- >>   3 files changed, 25 insertions(+), 1 deletion(-) >> > > With the following one nitpick addressed: > > Reviewed-by: Gavin Shan > >> diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/ >> asm/kvm_rme.h >> index d684b30493f5..67ee38541a82 100644 >> --- a/arch/arm64/include/asm/kvm_rme.h >> +++ b/arch/arm64/include/asm/kvm_rme.h >> @@ -85,6 +85,8 @@ void kvm_init_rme(void); >>   u32 kvm_realm_ipa_limit(void); >>   u32 kvm_realm_vgic_nr_lr(void); >>   +u64 kvm_realm_reset_id_aa64dfr0_el1(const struct kvm_vcpu *vcpu, >> u64 val); >> + >>   bool kvm_rme_supports_sve(void); >>     int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap >> *cap); >> diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c >> index f83f34358832..8c426f575728 100644 >> --- a/arch/arm64/kvm/rme.c >> +++ b/arch/arm64/kvm/rme.c >> @@ -87,6 +87,28 @@ u32 kvm_realm_vgic_nr_lr(void) >>       return u64_get_bits(rmm_feat_reg0, >> RMI_FEATURE_REGISTER_0_GICV3_NUM_LRS); >>   } >>   +u64 kvm_realm_reset_id_aa64dfr0_el1(const struct kvm_vcpu *vcpu, >> u64 val) >> +{ >> +    u32 bps = u64_get_bits(rmm_feat_reg0, >> RMI_FEATURE_REGISTER_0_NUM_BPS); >> +    u32 wps = u64_get_bits(rmm_feat_reg0, >> RMI_FEATURE_REGISTER_0_NUM_WPS); >> +    u32 ctx_cmps; >> + >> +    if (!kvm_is_realm(vcpu->kvm)) >> +        return val; >> + >> +    /* Ensure CTX_CMPs is still valid */ >> +    ctx_cmps = FIELD_GET(ID_AA64DFR0_EL1_CTX_CMPs, val); >> +    ctx_cmps = min(bps, ctx_cmps); >> + >> +    val &= ~(ID_AA64DFR0_EL1_BRPs_MASK | ID_AA64DFR0_EL1_WRPs_MASK | >> +         ID_AA64DFR0_EL1_CTX_CMPs); >> +    val |= FIELD_PREP(ID_AA64DFR0_EL1_BRPs_MASK, bps) | >> +           FIELD_PREP(ID_AA64DFR0_EL1_WRPs_MASK, wps) | >> +           FIELD_PREP(ID_AA64DFR0_EL1_CTX_CMPs, ctx_cmps); >> + >> +    return val; >> +} >> + > > The chunk of code can be squeezed to > sys_reg.c::sanitise_id_aa64dfr0_el1() since > sys_reg.c has been plumbed for realm, no reason to keep a separate > helper in rme.c > because it's only called by sys_reg.c::sanitise_id_aa64dfr0_el1() The issue here is the rmm_feat_reg0 variable - it's currently static in rme.c - so I can't just shift the code over. I could obviously provide helpers to get the necessary information but this seemed cleaner. Thanks, Steve >>   static int get_start_level(struct realm *realm) >>   { >>       return 4 - ((realm->ia_bits - 8) / (RMM_PAGE_SHIFT - 3)); >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c >> index ed881725eb64..5618eff33155 100644 >> --- a/arch/arm64/kvm/sys_regs.c >> +++ b/arch/arm64/kvm/sys_regs.c >> @@ -1820,7 +1820,7 @@ static u64 sanitise_id_aa64dfr0_el1(const struct >> kvm_vcpu *vcpu, u64 val) >>       /* Hide BRBE from guests */ >>       val &= ~ID_AA64DFR0_EL1_BRBE_MASK; >>   -    return val; >> +    return kvm_realm_reset_id_aa64dfr0_el1(vcpu, val); >>   } >>     static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, > > Thanks, > Gavin >