From mboxrd@z Thu Jan 1 00:00:00 1970 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 48B5915C15A for ; Fri, 29 Nov 2024 12:58:04 +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=1732885086; cv=none; b=jInNUgPlOd+DCuLfeHdnlk4MuDqdJ+iDoIT1y14KCdzmv7iqrU+bo1Cqj5I9mA6UPntNyOMm/mAuuyEhWVzlLa5c5xgkci6ztLgztEe6B+Rsa5/2RPcUJKALcW5PSRlvdGlWIC6MnLQid6u2N5vGKZcoOmexdm2oPm3SqXaOsr4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732885086; c=relaxed/simple; bh=N86aIaspaf9/OWHueYEllRRLdGM2qGulhJQm2YAviaA=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=mnbTYRm0qHlex1Bpa15Bf9pAG+sB/I9XvpnZQDjv1fJGxhUBJDYavAt67e69gQ+U+HTlBt0kBJ8k5/NwhVynh4BW/KcKQeX/c1OXJo7oG8My6iKI6ckmspTdmGGS+LZNd/16aXHrIsVol0tvfU/3pK+cWg4+mII+NFfNYCJnAzw= 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=QwG9SRjp; 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="QwG9SRjp" Received: by mail-ej1-f74.google.com with SMTP id a640c23a62f3a-aa53537b4c6so93595366b.2 for ; Fri, 29 Nov 2024 04:58:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1732885082; x=1733489882; darn=lists.linux.dev; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=iTo7mdsKhhMMv0NQ6W3WdpTpByHz4qODWqGMzHKiw1I=; b=QwG9SRjpYe7oiSVNag0q5CXPVF3Lv8spFO1TotD8stlfAFADX6Gr3CkQjcvos4KJZO uZHOSR0z7LhTxSk3bH7BCIZA8KgBYjQQYKGaf3T7GzYVWgyVORpoqLSu7WMeDkn+UkyK kS+lOsY9D+dzQCttuYidbg4P+Pu8b7lYCWZ3YRdMshTF/R18I9B+VZhZ3/QCmXbEu2C/ GJBIp4YyhiTD2X9+T3zro1MG9IIANcoiAp9BTVy7xJcEgVvUwJKwWTz0UKhNKzZBM9QC ahxzk5g0KSqbC0L5DSNGWNGB1dxArgpSTGJ66LhUsxiuj4LKw0mRotOcEqCDGlFracTj ySTA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732885082; x=1733489882; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=iTo7mdsKhhMMv0NQ6W3WdpTpByHz4qODWqGMzHKiw1I=; b=rvdWZ8Apn0N3ZMip5ym/C/EmOnW0PG4wCkV1E04kf/El2YrIKlDb3awFIZPD07e5u/ uXS+52qtcKbO23T/9y+9Of+givOZCcMCTKxMl2iHYW3mEqnCtlWABDumTOtjWb0ip0D4 2nSnSXFBtsYA1dNZVBzH7VjEbCD+akDluNT9OqUK+gp06FaEol21mamRPEJ3pE2C8iXZ dHNHZAe8D7owXOkjrvh8VFKXeRdxKG1CYG5DvY3tUQAK6QQo9toBnXF4xnZDLj79KcR5 hkaVrZvdL6q1lvsbGbT+tWQoUtn9fqbicoiVLQ3xE7nLdfYaRnP7VP75Wwcd6F5hk9Bi GYBQ== X-Forwarded-Encrypted: i=1; AJvYcCX6hSqJMOvMKIPOnqY107GaDObAq+ZyLUDW2IuFVdLre8mxWYmCSD6P5FW+HFbEoHWgfQeQm64=@lists.linux.dev X-Gm-Message-State: AOJu0YzxPJvI6OTUUbmc+kLAWef/DySHeC/3yZzphj0C8PEhZRZZEqM9 KspByg2q+LWKXRWxeIIPFOTRj74mB67R7ef0uB+5jjZcTwKb2eUuNSo/lzQ51zR80G3NNfHtzdx w17+LHw== X-Google-Smtp-Source: AGHT+IE8LI59tC+qSLoKQ9kpy+7UR4VBfF+klcw+nBIw6XFRR92RWRwAjYNKTrXAmiQZO9b0XnadXq1XxO3S X-Received: from edya11.prod.google.com ([2002:aa7:cf0b:0:b0:5cf:ca78:ecdf]) (user=qperret job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6402:4402:b0:5cf:f248:7715 with SMTP id 4fb4d7f45d1cf-5d080c48680mr9111559a12.23.1732885082703; Fri, 29 Nov 2024 04:58:02 -0800 (PST) Date: Fri, 29 Nov 2024 12:58:00 +0000 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.47.0.338.g60cca15819-goog Message-ID: <20241129125800.992468-1-qperret@google.com> Subject: [PATCH] KVM: arm64: Selftest for pKVM transitions From: Quentin Perret To: Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, qperret@google.com Content-Type: text/plain; charset="UTF-8" We have recently found a bug [1] in the pKVM memory ownership transitions by code inspection, but it could have been caught with a test. Introduce a boot-time selftest exercising all the known pKVM memory transitions and importantly checks the rejection of illegal transitions. The new test is hidden behind a new Kconfig option separate from CONFIG_EL2_NVHE_DEBUG on purpose as that has side effects on the transition checks ([1] doesn't reproduce with EL2 debug enabled). [1] https://lore.kernel.org/kvmarm/20241128154406.602875-1-qperret@google.com/ Suggested-by: Will Deacon Signed-off-by: Quentin Perret --- arch/arm64/kvm/Kconfig | 10 ++ arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 6 + arch/arm64/kvm/hyp/nvhe/mem_protect.c | 110 ++++++++++++++++++ arch/arm64/kvm/hyp/nvhe/setup.c | 2 + 4 files changed, 128 insertions(+) diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index ead632ad01b4..038d7f52232c 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -46,6 +46,7 @@ menuconfig KVM config NVHE_EL2_DEBUG bool "Debug mode for non-VHE EL2 object" depends on KVM + select PKVM_SELFTESTS help Say Y here to enable the debug mode for the non-VHE KVM EL2 object. Failure reports will BUG() in the hypervisor. This is intended for @@ -53,6 +54,15 @@ config NVHE_EL2_DEBUG If unsure, say N. +config PKVM_SELFTESTS + bool "Protected KVM hypervisor selftests" + help + Say Y here to enable Protected KVM (pKVM) hypervisor selftests + during boot. Failure reports will panic the hypervisor. This is + intended for EL2 hypervisor development. + + If unsure, say N. + config PROTECTED_NVHE_STACKTRACE bool "Protected KVM hypervisor stacktraces" depends on NVHE_EL2_DEBUG diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h index 0972faccc2af..a9b2677227cc 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h @@ -90,4 +90,10 @@ static __always_inline void __load_host_stage2(void) else write_sysreg(0, vttbr_el2); } + +#ifdef CONFIG_PKVM_SELFTESTS +void pkvm_ownership_selftest(void); +#else +static inline void pkvm_ownership_selftest(void) { } +#endif #endif /* __KVM_NVHE_MEM_PROTECT__ */ diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index e75374d682f4..6a01ffe3d117 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -1306,3 +1306,113 @@ int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages) return ret; } + +#ifdef CONFIG_PKVM_SELFTESTS +struct pkvm_expected_state { + enum pkvm_page_state host; + enum pkvm_page_state hyp; +}; + +static struct pkvm_expected_state selftest_state; +static struct hyp_page *selftest_page; + +static void assert_page_state(void) +{ + void *virt = hyp_page_to_virt(selftest_page); + u64 size = PAGE_SIZE << selftest_page->order; + u64 phys = hyp_virt_to_phys(virt); + + host_lock_component(); + WARN_ON(__host_check_page_state_range(phys, size, selftest_state.host)); + host_unlock_component(); + + hyp_lock_component(); + WARN_ON(__hyp_check_page_state_range((u64)virt, size, selftest_state.hyp)); + hyp_unlock_component(); +} + +#define assert_transition_res(res, fn, ...) \ + do { \ + WARN_ON(fn(__VA_ARGS__) != res); \ + assert_page_state(); \ + } while (0) + +void pkvm_ownership_selftest(void) +{ + void *virt = hyp_alloc_pages(&host_s2_pool, 0); + u64 phys, size, pfn; + + WARN_ON(!virt); + selftest_page = hyp_virt_to_page(virt); + selftest_page->refcount = 0; + + size = PAGE_SIZE << selftest_page->order; + phys = hyp_virt_to_phys(virt); + pfn = hyp_phys_to_pfn(phys); + + selftest_state.host = PKVM_NOPAGE; + selftest_state.hyp = PKVM_PAGE_OWNED; + assert_page_state(); + assert_transition_res(-EPERM, __pkvm_host_donate_hyp, pfn, 1); + assert_transition_res(-EPERM, __pkvm_host_share_hyp, pfn); + assert_transition_res(-EPERM, __pkvm_host_unshare_hyp, pfn); + assert_transition_res(-EPERM, __pkvm_host_share_ffa, pfn, 1); + assert_transition_res(-EPERM, __pkvm_host_unshare_ffa, pfn, 1); + assert_transition_res(-EPERM, hyp_pin_shared_mem, virt, virt + size); + + selftest_state.host = PKVM_PAGE_OWNED; + selftest_state.hyp = PKVM_NOPAGE; + assert_transition_res(0, __pkvm_hyp_donate_host, pfn, 1); + assert_transition_res(-EPERM, __pkvm_hyp_donate_host, pfn, 1); + assert_transition_res(-EPERM, hyp_pin_shared_mem, virt, virt + size); + + selftest_state.host = PKVM_PAGE_SHARED_OWNED; + selftest_state.hyp = PKVM_PAGE_SHARED_BORROWED; + assert_transition_res(0, __pkvm_host_share_hyp, pfn); + assert_transition_res(-EPERM, __pkvm_host_share_hyp, pfn); + assert_transition_res(-EPERM, __pkvm_host_donate_hyp, pfn, 1); + assert_transition_res(-EPERM, __pkvm_host_share_ffa, pfn, 1); + assert_transition_res(-EPERM, __pkvm_hyp_donate_host, pfn, 1); + + assert_transition_res(0, hyp_pin_shared_mem, virt, virt + size); + WARN_ON(!hyp_page_count(virt)); + assert_transition_res(-EBUSY, __pkvm_host_unshare_hyp, pfn); + assert_transition_res(-EPERM, __pkvm_host_share_hyp, pfn); + assert_transition_res(-EPERM, __pkvm_host_donate_hyp, pfn, 1); + assert_transition_res(-EPERM, __pkvm_host_share_ffa, pfn, 1); + assert_transition_res(-EPERM, __pkvm_hyp_donate_host, pfn, 1); + + hyp_unpin_shared_mem(virt, virt + size); + assert_page_state(); + WARN_ON(hyp_page_count(virt)); + assert_transition_res(-EPERM, __pkvm_host_share_hyp, pfn); + assert_transition_res(-EPERM, __pkvm_host_donate_hyp, pfn, 1); + assert_transition_res(-EPERM, __pkvm_host_share_ffa, pfn, 1); + assert_transition_res(-EPERM, __pkvm_hyp_donate_host, pfn, 1); + + selftest_state.host = PKVM_PAGE_OWNED; + selftest_state.hyp = PKVM_NOPAGE; + assert_transition_res(0, __pkvm_host_unshare_hyp, pfn); + + selftest_state.host = PKVM_PAGE_SHARED_OWNED; + selftest_state.hyp = PKVM_NOPAGE; + assert_transition_res(0, __pkvm_host_share_ffa, pfn, 1); + assert_transition_res(-EPERM, __pkvm_host_share_ffa, pfn, 1); + assert_transition_res(-EPERM, __pkvm_host_donate_hyp, pfn, 1); + assert_transition_res(-EPERM, __pkvm_host_share_hyp, pfn); + assert_transition_res(-EPERM, __pkvm_host_unshare_hyp, pfn); + assert_transition_res(-EPERM, __pkvm_hyp_donate_host, pfn, 1); + assert_transition_res(-EPERM, hyp_pin_shared_mem, virt, virt + size); + + selftest_state.host = PKVM_PAGE_OWNED; + selftest_state.hyp = PKVM_NOPAGE; + assert_transition_res(0, __pkvm_host_unshare_ffa, pfn, 1); + + selftest_state.host = PKVM_NOPAGE; + selftest_state.hyp = PKVM_PAGE_OWNED; + assert_transition_res(0, __pkvm_host_donate_hyp, pfn, 1); + + selftest_page->refcount = 1; + hyp_put_page(&host_s2_pool, virt); +} +#endif diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c index cbdd18cd3f98..d154e80fe6b9 100644 --- a/arch/arm64/kvm/hyp/nvhe/setup.c +++ b/arch/arm64/kvm/hyp/nvhe/setup.c @@ -306,6 +306,8 @@ void __noreturn __pkvm_init_finalise(void) goto out; pkvm_hyp_vm_table_init(vm_table_base); + + pkvm_ownership_selftest(); out: /* * We tail-called to here from handle___pkvm_init() and will not return, -- 2.47.0.338.g60cca15819-goog