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bh=U7Ezu9BWvQQl3+odVqPz50z5xQDmhHP5/rCWfk/q+sQ=; b=mY8kuxjQObwrg2hTDwBS3ERX5p1Dpq8EGbFp/nK3sQd0j/SChQ6CnIu/5ZyG/goLBd bEm0QWonEguzQ0FDMRsEuMw9xgycJLw4+snFjq09GTH/zpeqBNApHefAYzA1LcmCYbUa kmItRAqEmAWnVH4/ibPsZRfM81soR+KspTEYEBVLI/mun6I18OGicqQm6RAFufRY9cOB leee5kajK6n6AA8nTaMEqQA25Cau33JtNVft5Z8cqQ2Su93DrLogo2OJjcvPDtwvDJKh oUinflroBRgyhzrfIfQrzLBQJujPgcdbkJjHYEjVwA2AupEYfai93/f30ef+PVat2RW8 eaog== X-Gm-Message-State: AOAM530f0jGZFnFQqqkrs9tu2hgRip8SU36xIYiCyvhr/CnHwxVeuaG0 +TrX7jp0Zcjqpl0ES+I81KBMstHqcTKs 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 Cc: devicetree@vger.kernel.org, android-kvm@google.com, linux-kernel@vger.kernel.org, Fuad Tabba , kernel-team@android.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu 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) } -- 2.30.0.284.gd98b1dd5eaa7-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm