From: Quentin Perret <qperret@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>
Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE"
<devicetree@vger.kernel.org>,
android-kvm@google.com, open list <linux-kernel@vger.kernel.org>,
kernel-team@android.com,
"open list:KERNEL VIRTUAL MACHINE FOR ARM64 \(KVM/arm64\)"
<kvmarm@lists.cs.columbia.edu>,
"moderated list:ARM64 PORT \(AARCH64 ARCHITECTURE\)"
<linux-arm-kernel@lists.infradead.org>
Subject: [RFC PATCH 07/27] KVM: arm64: Introduce a BSS section for use at Hyp
Date: Tue, 17 Nov 2020 18:15:47 +0000 [thread overview]
Message-ID: <20201117181607.1761516-8-qperret@google.com> (raw)
In-Reply-To: <20201117181607.1761516-1-qperret@google.com>
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 <qperret@google.com>
---
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 4382b5d0645d..ded78a25365d 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 <asm-generic/vmlinux.lds.h>
#include <asm/cache.h>
#include <asm/hyp_image.h>
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 7335eb4fb0bd..882eb383bd75 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1709,7 +1709,18 @@ 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)
}
--
2.29.2.299.gdc1121823c-goog
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next prev parent reply other threads:[~2020-11-17 18:16 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-17 18:15 [RFC PATCH 00/27] KVM/arm64: A stage 2 for the host Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 01/27] arm64: lib: Annotate {clear, copy}_page() as position-independent Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 02/27] KVM: arm64: Link position-independent string routines into .hyp.text Quentin Perret
2020-11-23 12:34 ` David Brazdil
2020-11-23 14:06 ` Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 03/27] KVM: arm64: Add standalone ticket spinlock implementation for use at hyp Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 04/27] KVM: arm64: Initialize kvm_nvhe_init_params early Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 05/27] KVM: arm64: Avoid free_page() in page-table allocator Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 06/27] KVM: arm64: Factor memory allocation out of pgtable.c Quentin Perret
2020-11-17 18:15 ` Quentin Perret [this message]
2020-11-17 18:15 ` [RFC PATCH 08/27] KVM: arm64: Make kvm_call_hyp() a function call at Hyp Quentin Perret
2020-11-23 12:51 ` David Brazdil
2020-11-17 18:15 ` [RFC PATCH 09/27] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code Quentin Perret
2020-11-23 12:57 ` David Brazdil
2020-11-23 14:02 ` Quentin Perret
2020-11-23 14:54 ` David Brazdil
2020-11-17 18:15 ` [RFC PATCH 10/27] KVM: arm64: Introduce an early Hyp page allocator Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 11/27] KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 12/27] KVM: arm64: Introduce a Hyp buddy page allocator Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 13/27] KVM: arm64: Enable access to sanitized CPU features at EL2 Quentin Perret
2020-11-23 10:55 ` Fuad Tabba
2020-11-23 13:51 ` Quentin Perret
2020-11-23 13:22 ` David Brazdil
2020-11-23 14:39 ` Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 14/27] KVM: arm64: Factor out vector address calculation Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 15/27] of/fdt: Introduce early_init_dt_add_memory_hyp() Quentin Perret
2020-11-17 19:44 ` Rob Herring
2020-11-18 9:25 ` Quentin Perret
2020-11-18 14:31 ` Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 16/27] KVM: arm64: Prepare Hyp memory protection Quentin Perret
2020-12-03 12:57 ` Fuad Tabba
2020-12-04 18:01 ` Quentin Perret
2020-12-07 10:20 ` Will Deacon
2020-12-07 11:05 ` Mark Rutland
2020-12-07 11:10 ` Will Deacon
2020-12-07 11:14 ` Fuad Tabba
2020-12-07 11:16 ` Fuad Tabba
2020-12-07 11:58 ` Quentin Perret
2020-12-07 13:54 ` Marc Zyngier
2020-12-07 14:17 ` Quentin Perret
2020-12-07 13:40 ` Will Deacon
2020-12-07 14:11 ` Quentin Perret
2020-12-08 9:40 ` Will Deacon
2020-11-17 18:15 ` [RFC PATCH 17/27] KVM: arm64: Elevate Hyp mappings creation at EL2 Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 18/27] KVM: arm64: Use kvm_arch for stage 2 pgtable Quentin Perret
2020-11-17 18:15 ` [RFC PATCH 19/27] KVM: arm64: Use kvm_arch in kvm_s2_mmu Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 20/27] KVM: arm64: Set host stage 2 using kvm_nvhe_init_params Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 21/27] KVM: arm64: Refactor kvm_arm_setup_stage2() Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 22/27] KVM: arm64: Refactor __load_guest_stage2() Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 23/27] KVM: arm64: Refactor __populate_fault_info() Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 24/27] KVM: arm64: Make memcache anonymous in pgtable allocator Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 25/27] KVM: arm64: Reserve memory for host stage 2 Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 26/27] KVM: arm64: Sort the memblock regions list Quentin Perret
2020-11-17 18:16 ` [RFC PATCH 27/27] KVM: arm64: Wrap the host with a stage 2 Quentin Perret
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