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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=U7Ezu9BWvQQl3+odVqPz50z5xQDmhHP5/rCWfk/q+sQ=; b=iqru/0ql/vWGVFuvJd/VQ9ZrJy+RV7adPKrB+YPqopT11f+0YZOjQ8PceFRloJLqON gROXDuiDpOeV4sXI2VPA7M6J2J7XJED9E12k1Gc2u3DvNXRR78bDunnrBZomLLb7jIR3 iUJDds+qo/ZNpb295bI+doNE+WRSvugHnfiYPRIidzOfCO2j3lijTqoTK+Zhp4jvVYol lOPBsNPX2j7nc9xhrXuGXJkosz6JRN7OoHJhXdu407Eo2cElAxccqZgL+MmuPcSb9Lc2 cSqgRE+Zx9EkGcMjjo/ibdSAWUhhwTnLrt0K9TWDyxfKd1aJl1HE2KVOBS5Of8188//T TJiA== X-Gm-Message-State: AOAM530UgowfgGm9MQQ8pVLvoH0yVjDr66m+TBPDGdqROF/OBsGCD0x2 INlwtkEOt/Ha/WZGcizCVxsDktDiAg4w X-Google-Smtp-Source: ABdhPJw/4cr8P48R7RVf1xArteNINTq8P74DXyz+B4OUiC/ZzBFlkO7kRqbd09zSVKPjQ4dVKp1TcQnazFJK X-Received: from r2d2-qp.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:1652]) (user=qperret job=sendgmr) by 2002:a0c:ea34:: with SMTP id t20mr3195107qvp.5.1610108141217; Fri, 08 Jan 2021 04:15:41 -0800 (PST) Date: Fri, 8 Jan 2021 12:15:05 +0000 In-Reply-To: <20210108121524.656872-1-qperret@google.com> Message-Id: <20210108121524.656872-8-qperret@google.com> Mime-Version: 1.0 References: <20210108121524.656872-1-qperret@google.com> X-Mailer: git-send-email 2.30.0.284.gd98b1dd5eaa7-goog Subject: [RFC PATCH v2 07/26] KVM: arm64: Introduce a BSS section for use at Hyp From: Quentin Perret To: Catalin Marinas , Will Deacon , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , Rob Herring , Frank Rowand X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210108_071548_884303_A1EF8A52 X-CRM114-Status: GOOD ( 16.66 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , devicetree@vger.kernel.org, android-kvm@google.com, linux-kernel@vger.kernel.org, Fuad Tabba , David Brazdil , kernel-team@android.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Currently, the hyp code cannot make full use of a bss, as the kernel section is mapped read-only. While this mapping could simply be changed to read-write, it would intermingle even more the hyp and kernel state than they currently are. Instead, introduce a __hyp_bss section, that uses reserved pages, and create the appropriate RW hyp mappings during KVM init. Signed-off-by: Quentin Perret --- arch/arm64/include/asm/sections.h | 1 + arch/arm64/kernel/vmlinux.lds.S | 7 +++++++ arch/arm64/kvm/arm.c | 11 +++++++++++ arch/arm64/kvm/hyp/nvhe/hyp.lds.S | 1 + 4 files changed, 20 insertions(+) diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h index 8ff579361731..f58cf493de16 100644 --- a/arch/arm64/include/asm/sections.h +++ b/arch/arm64/include/asm/sections.h @@ -12,6 +12,7 @@ extern char __hibernate_exit_text_start[], __hibernate_exit_text_end[]; extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[]; extern char __hyp_text_start[], __hyp_text_end[]; extern char __hyp_data_ro_after_init_start[], __hyp_data_ro_after_init_end[]; +extern char __hyp_bss_start[], __hyp_bss_end[]; extern char __idmap_text_start[], __idmap_text_end[]; extern char __initdata_begin[], __initdata_end[]; extern char __inittext_begin[], __inittext_end[]; diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 43af13968dfd..3eca35d5a7cf 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -8,6 +8,13 @@ #define RO_EXCEPTION_TABLE_ALIGN 8 #define RUNTIME_DISCARD_EXIT +#define BSS_FIRST_SECTIONS \ + . = ALIGN(PAGE_SIZE); \ + __hyp_bss_start = .; \ + *(.hyp.bss) \ + . = ALIGN(PAGE_SIZE); \ + __hyp_bss_end = .; + #include #include #include diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 3ac0f3425833..51b53ca36dc5 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -1770,7 +1770,18 @@ static int init_hyp_mode(void) goto out_err; } + /* + * .hyp.bss is placed at the beginning of the .bss section, so map that + * part RW, and the rest RO as the hyp shouldn't be touching it. + */ err = create_hyp_mappings(kvm_ksym_ref(__bss_start), + kvm_ksym_ref(__hyp_bss_end), PAGE_HYP); + if (err) { + kvm_err("Cannot map hyp bss section: %d\n", err); + goto out_err; + } + + err = create_hyp_mappings(kvm_ksym_ref(__hyp_bss_end), kvm_ksym_ref(__bss_stop), PAGE_HYP_RO); if (err) { kvm_err("Cannot map bss section\n"); diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S index 5d76ff2ba63e..dc281d90063e 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S +++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S @@ -17,4 +17,5 @@ SECTIONS { PERCPU_INPUT(L1_CACHE_BYTES) } HYP_SECTION(.data..ro_after_init) + HYP_SECTION(.bss) }