From nobody Mon Feb 9 16:06:11 2026 Received: from mail-ej1-f74.google.com (mail-ej1-f74.google.com [209.85.218.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A9BD211715 for ; Wed, 16 Apr 2025 15:27:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744817228; cv=none; b=TKzWQKOQ5hQQ2GaZW1vzKo9nlnDIlw1i+UhKTkn0ojjD7D64oh9D2wmj4mlMObFqN2cu7vH4eUbuctNsq0enlkjH0OlANccutt+wRSZURrjeq0rVtqMkwBwJOt/B4+F5X4mQbXxKIzj4WcjY/A/l7HhjmN+XXbB6b3SR5U/w8Ow= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744817228; c=relaxed/simple; bh=mlPlfdc/NWwYqy2zjYwAzNRWIZhZ7ZZR38Y6Ldz2Cr0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Ee6AYKtVne4UMhgsjT1KGb2fSumSP+gZ2ozoHGDLIihZ0e557r2AA6e2L1rud/RsqEsBAP3mzqTYtF3jIiIGNvoRkByNd342HugbS1f5iVIK5+PsDZc9+trCm+OaAIA8mZ2haepRBkVOrPiM1MOlIIgB+jprV8tqgijOLcEOB3o= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--qperret.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=rNayNeQD; arc=none smtp.client-ip=209.85.218.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--qperret.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="rNayNeQD" Received: by mail-ej1-f74.google.com with SMTP id a640c23a62f3a-ac3dca41591so620226066b.1 for ; Wed, 16 Apr 2025 08:27:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1744817224; x=1745422024; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=VYU32RrZwSVxBTFJfFZ/zcmulUROASDhu21QhFFvtpI=; b=rNayNeQDPSxQYMnciZNcdl7/kUmhK16bMPGV70Gxg5zzBD/MLjOXtAzRXFXk4tGkCI rImmHevMX1axjiPTW14omZr7+wKAGB0Qf4zWr7ZmQtbWGkD8tZzIxYEx56fIGYBH8lgb 4+8YLYILzeweoplpMqIGIOGF2ozD557XlXDUqWgyiwF0nQdmoAm2sbU40hNner/8BWsX wCx0XppMyPhUm0DpVB8vTy4rYv8qkB7HxYaoIKeIqNoevC3gLBHDuG0+DMbShP4Jl/7p BaGCuJdQi+Fsz7GSgK7yzaYuoYu6ABy1elFdI7AKPmEqoy8G/BwYWxhgNsDlTP6DkLTM VB3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744817224; x=1745422024; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=VYU32RrZwSVxBTFJfFZ/zcmulUROASDhu21QhFFvtpI=; b=S4dOyaP6oDwjI+IZeQbcbQYCDwM0n5jl5DgKW1/CwUFYnPvVWOlEwqkl/1kwM5MMux 3OrgMVXqLm+XqISl6JXgSZTYMuKhhtRsWTEJQ+33+AVZMw3zNpOTzyG5FnSe5bxhm1Uh BQFxTgiuFcybkKynGwD2FHqcOyxveakBJ5JZEBinQNKlftvmO251do+zWbS6RuYrxkgI mJBO7+m8v/9uD13/8ZihXxEraE5hhJWSoUe2FNoDmmzbGE//h9APmFsAiSP9z2drFCau fjrWLAmAtgVkdLBaQ4TuKeQcJt1ED3FL9Y5l6oF+JW0lBfpS+OLklLNVXk1NwGHa/rOh 3pVQ== X-Forwarded-Encrypted: i=1; AJvYcCV3xyqOqCrjx5ylQo0Fzp2W+rDXWU8deL23Mj4nkFgIDrxzks4vzAY5cgpKUMBLHCKIMLlcwj2s9YpjnB8=@vger.kernel.org X-Gm-Message-State: AOJu0YxHSgtZSViLQO7O/1vlYcnx7nyreR2TngclXAXanBGuYTL/+0I7 TrgQ2PEu4Od8TXB1Y32sWmAlLRWPuKfr5CKBWQLdGNvEO/X9grF+EgaRLv9PhyZUFLtoII9LSl6 OSwtdKA== X-Google-Smtp-Source: AGHT+IFx/wZB15eiIdBs2Eh1Wi5DlZDuOgycITN7QmUrR/0Pho2JFdCK7PrHfR8mLm6W9F5WKdLs/Vk8CDxe X-Received: from edyc19.prod.google.com ([2002:aa7:df13:0:b0:5ec:dada:a73e]) (user=qperret job=prod-delivery.src-stubby-dispatcher) by 2002:a17:906:478a:b0:ac7:cfe0:3014 with SMTP id a640c23a62f3a-acb4296492fmr220940266b.25.1744817224502; Wed, 16 Apr 2025 08:27:04 -0700 (PDT) Date: Wed, 16 Apr 2025 15:26:46 +0000 In-Reply-To: <20250416152648.2982950-1-qperret@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250416152648.2982950-1-qperret@google.com> X-Mailer: git-send-email 2.49.0.604.gff1f9ca942-goog Message-ID: <20250416152648.2982950-7-qperret@google.com> Subject: [PATCH v2 6/7] KVM: arm64: Defer EL2 stage-1 mapping on share From: Quentin Perret To: Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon Cc: Vincent Donnefort , Fuad Tabba , Quentin Perret , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" We currently blindly map into EL2 stage-1 *any* page passed to the __pkvm_host_share_hyp() HVC. This is less than ideal from a security perspective as it makes exploitation of potential hypervisor gadgets easier than it should be. But interestingly, pKVM should never need to access SHARED_BORROWED pages that it hasn't previously pinned, so there is no need to map the page before that. Reviewed-by: Marc Zyngier Signed-off-by: Quentin Perret --- arch/arm64/kvm/hyp/nvhe/mem_protect.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvh= e/mem_protect.c index 25ff84c053c1..91b757e3fb4c 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -693,7 +693,6 @@ static int __guest_check_page_state_range(struct pkvm_h= yp_vcpu *vcpu, u64 addr, int __pkvm_host_share_hyp(u64 pfn) { u64 phys =3D hyp_pfn_to_phys(pfn); - void *virt =3D __hyp_va(phys); u64 size =3D PAGE_SIZE; int ret; =20 @@ -710,7 +709,6 @@ int __pkvm_host_share_hyp(u64 pfn) } =20 __hyp_set_page_state_range(phys, size, PKVM_PAGE_SHARED_BORROWED); - WARN_ON(pkvm_create_mappings_locked(virt, virt + size, PAGE_HYP)); WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED)); =20 unlock: @@ -742,7 +740,6 @@ int __pkvm_host_unshare_hyp(u64 pfn) } =20 __hyp_set_page_state_range(phys, size, PKVM_NOPAGE); - WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, virt, size) !=3D size); WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_OWNED)); =20 unlock: @@ -818,6 +815,7 @@ int hyp_pin_shared_mem(void *from, void *to) u64 end =3D PAGE_ALIGN((u64)to); u64 phys =3D __hyp_pa(start); u64 size =3D end - start; + struct hyp_page *p; int ret; =20 host_lock_component(); @@ -831,8 +829,14 @@ int hyp_pin_shared_mem(void *from, void *to) if (ret) goto unlock; =20 - for (cur =3D start; cur < end; cur +=3D PAGE_SIZE) - hyp_page_ref_inc(hyp_virt_to_page(cur)); + for (cur =3D start; cur < end; cur +=3D PAGE_SIZE) { + p =3D hyp_virt_to_page(cur); + hyp_page_ref_inc(p); + if (p->refcount =3D=3D 1) + WARN_ON(pkvm_create_mappings_locked((void *)cur, + (void *)cur + PAGE_SIZE, + PAGE_HYP)); + } =20 unlock: hyp_unlock_component(); @@ -845,12 +849,17 @@ void hyp_unpin_shared_mem(void *from, void *to) { u64 cur, start =3D ALIGN_DOWN((u64)from, PAGE_SIZE); u64 end =3D PAGE_ALIGN((u64)to); + struct hyp_page *p; =20 host_lock_component(); hyp_lock_component(); =20 - for (cur =3D start; cur < end; cur +=3D PAGE_SIZE) - hyp_page_ref_dec(hyp_virt_to_page(cur)); + for (cur =3D start; cur < end; cur +=3D PAGE_SIZE) { + p =3D hyp_virt_to_page(cur); + if (p->refcount =3D=3D 1) + WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, cur, PAGE_SIZE) !=3D PAGE_= SIZE); + hyp_page_ref_dec(p); + } =20 hyp_unlock_component(); host_unlock_component(); --=20 2.49.0.604.gff1f9ca942-goog