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From: Andrew Scull <ascull@google.com>
To: kvmarm@lists.cs.columbia.edu
Cc: maz@kernel.org, kernel-team@android.com
Subject: [PATCH 05/37] KVM: arm64: nVHE: Break out of the hyp-init idmap
Date: Wed, 15 Jul 2020 19:44:06 +0100
Message-ID: <20200715184438.1390996-6-ascull@google.com> (raw)
In-Reply-To: <20200715184438.1390996-1-ascull@google.com>

The idmap is a restrictive context as it is located separately from the
rest of hyp. Extra care must be taken to avoid symbol references that
will not resolve correctly so, the less that has to be done in this
context, the better.

To overcome this, pass an pre-resolved pointer into hyp-init that it can
jump to and escape the idmap once it has installed the page table.

This patch just introduces the mechanism to break out of the idmap for
use in future changes.

Signed-off-by: Andrew Scull <ascull@google.com>
---
 arch/arm64/kvm/arm.c                |  7 ++++++-
 arch/arm64/kvm/hyp/nvhe/Makefile    |  3 ++-
 arch/arm64/kvm/hyp/nvhe/hyp-init.S  | 13 +++++++------
 arch/arm64/kvm/hyp/nvhe/hyp-start.S | 16 ++++++++++++++++
 4 files changed, 31 insertions(+), 8 deletions(-)
 create mode 100644 arch/arm64/kvm/hyp/nvhe/hyp-start.S

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index bf662c0dd409..52be6149fcbf 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1257,9 +1257,12 @@ long kvm_arch_vm_ioctl(struct file *filp,
 
 static void cpu_init_hyp_mode(void)
 {
+	DECLARE_KVM_NVHE_SYM(__kvm_hyp_start);
+
 	phys_addr_t pgd_ptr;
 	unsigned long hyp_stack_ptr;
 	unsigned long vector_ptr;
+	unsigned long start_hyp;
 	unsigned long tpidr_el2;
 
 	/* Switch from the HYP stub to our own HYP init vector */
@@ -1277,6 +1280,7 @@ static void cpu_init_hyp_mode(void)
 	hyp_stack_ptr = __this_cpu_read(kvm_arm_hyp_stack_page) + PAGE_SIZE;
 	hyp_stack_ptr = kern_hyp_va(hyp_stack_ptr);
 	vector_ptr = (unsigned long)kvm_get_hyp_vector();
+	start_hyp = (unsigned long)kern_hyp_va(kvm_ksym_ref_nvhe(__kvm_hyp_start));
 
 	/*
 	 * Call initialization code, and switch to the full blown HYP code.
@@ -1285,7 +1289,8 @@ static void cpu_init_hyp_mode(void)
 	 * cpus_have_const_cap() wrapper.
 	 */
 	BUG_ON(!system_capabilities_finalized());
-	__kvm_call_hyp((void *)pgd_ptr, hyp_stack_ptr, vector_ptr, tpidr_el2);
+	__kvm_call_hyp((void *)pgd_ptr, hyp_stack_ptr, vector_ptr, start_hyp,
+		       tpidr_el2);
 
 	/*
 	 * Disabling SSBD on a non-VHE system requires us to enable SSBS
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 0b34414557d6..1f3a39efaa6e 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -6,7 +6,8 @@
 asflags-y := -D__KVM_NVHE_HYPERVISOR__
 ccflags-y := -D__KVM_NVHE_HYPERVISOR__
 
-obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o
+obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o \
+	 hyp-start.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o
 
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index f80f169a8442..029c51365d03 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -46,13 +46,17 @@ __invalid:
 	 * x0: HYP pgd
 	 * x1: HYP stack
 	 * x2: HYP vectors
-	 * x3: per-CPU offset
+	 * x3: __kvm_hyp_start HYP address
+	 * x4: per-CPU offset
 	 */
 __do_hyp_init:
 	/* Check for a stub HVC call */
 	cmp	x0, #HVC_STUB_HCALL_NR
 	b.lo	__kvm_handle_stub_hvc
 
+	/* Set tpidr_el2 for use by HYP */
+	msr	tpidr_el2, x4
+
 	phys_to_ttbr x4, x0
 alternative_if ARM64_HAS_CNP
 	orr	x4, x4, #TTBR_CNP_BIT
@@ -116,11 +120,8 @@ alternative_else_nop_endif
 	mov	sp, x1
 	msr	vbar_el2, x2
 
-	/* Set tpidr_el2 for use by HYP */
-	msr	tpidr_el2, x3
-
-	/* Hello, World! */
-	eret
+	/* Leave the idmap posthaste and head over to __kvm_hyp_start */
+	br	x3
 SYM_CODE_END(__kvm_hyp_init)
 
 SYM_CODE_START(__kvm_handle_stub_hvc)
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-start.S b/arch/arm64/kvm/hyp/nvhe/hyp-start.S
new file mode 100644
index 000000000000..5f7fbcb57fd5
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-start.S
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 - Google Inc
+ * Author: Andrew Scull <ascull@google.com>
+ */
+
+#include <linux/linkage.h>
+
+#include <asm/assembler.h>
+#include <asm/asm-offsets.h>
+#include <asm/kvm_asm.h>
+
+SYM_CODE_START(__kvm_hyp_start)
+	/* Hello, World! */
+	eret
+SYM_CODE_END(__kvm_hyp_start)
-- 
2.27.0.389.gc38d7665816-goog

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  parent reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-15 18:44 [PATCH 00/37] Transform the host into a vCPU Andrew Scull
2020-07-15 18:44 ` [PATCH 01/37] smccc: Make constants available to assembly Andrew Scull
2020-07-15 18:44 ` [PATCH 02/37] KVM: arm64: Move clearing of vcpu debug dirty bit Andrew Scull
2020-07-15 18:44 ` [PATCH 03/37] KVM: arm64: Track running vCPU outside of the CPU context Andrew Scull
2020-07-15 18:44 ` [PATCH 04/37] KVM: arm64: nVHE: Pass pointers consistently to hyp-init Andrew Scull
2020-07-15 18:44 ` Andrew Scull [this message]
2020-07-15 18:44 ` [PATCH 06/37] KVM: arm64: Only check pending interrupts if it would trap Andrew Scull
2020-07-17 16:21   ` Marc Zyngier
2020-07-15 18:44 ` [PATCH 07/37] KVM: arm64: Separate SError detection from VAXorcism Andrew Scull
2020-07-18  9:00   ` Marc Zyngier
2020-07-20 14:13     ` Andrew Scull
2020-07-20 14:56       ` Marc Zyngier
2020-07-23  0:59         ` FW: " Renters Cancellation Requests
2020-07-20 15:40   ` Andrew Scull
2020-07-20 15:57     ` Marc Zyngier
2020-07-15 18:44 ` [PATCH 08/37] KVM: arm64: nVHE: Introduce a hyp run loop for the host Andrew Scull
2020-07-15 18:44 ` [PATCH 09/37] smccc: Cast arguments to unsigned long Andrew Scull
2020-07-15 18:44 ` [PATCH 10/37] KVM: arm64: nVHE: Migrate hyp interface to SMCCC Andrew Scull
2020-07-15 18:44 ` [PATCH 11/37] KVM: arm64: nVHE: Migrate hyp-init " Andrew Scull
2020-07-15 18:44 ` [PATCH 12/37] KVM: arm64: nVHE: Fix pointers during SMCCC convertion Andrew Scull
2020-07-15 18:44 ` [PATCH 13/37] KVM: arm64: Rename workaround 2 helpers Andrew Scull
2020-07-15 18:44 ` [PATCH 14/37] KVM: arm64: nVHE: Use __kvm_vcpu_run for the host vcpu Andrew Scull
2020-07-15 18:44 ` [PATCH 15/37] KVM: arm64: Share some context save and restore macros Andrew Scull
2020-07-15 18:44 ` [PATCH 16/37] KVM: arm64: nVHE: Handle stub HVCs in the host loop Andrew Scull
2020-07-15 18:44 ` [PATCH 17/37] KVM: arm64: nVHE: Store host sysregs in host vcpu Andrew Scull
2020-07-15 18:44 ` [PATCH 18/37] KVM: arm64: nVHE: Access pmu_events directly in kvm_host_data Andrew Scull
2020-07-15 18:44 ` [PATCH 19/37] KVM: arm64: nVHE: Drop host_ctxt argument for context switching Andrew Scull
2020-07-15 18:44 ` [PATCH 20/37] KVM: arm64: nVHE: Use host vcpu context for host debug state Andrew Scull
2020-07-15 18:44 ` [PATCH 21/37] KVM: arm64: Move host debug state from vcpu to percpu Andrew Scull
2020-07-15 18:44 ` [PATCH 22/37] KVM: arm64: nVHE: Store host's mdcr_el2 and hcr_el2 in its vcpu Andrew Scull
2020-07-15 18:44 ` [PATCH 23/37] KVM: arm64: Skip __hyp_panic and go direct to hyp_panic Andrew Scull
2020-07-15 18:44 ` [PATCH 24/37] KVM: arm64: Break apart kvm_host_data Andrew Scull
2020-07-15 18:44 ` [PATCH 25/37] KVM: arm64: nVHE: Unify sysreg state saving paths Andrew Scull
2020-07-15 18:44 ` [PATCH 26/37] KVM: arm64: nVHE: Unify 32-bit sysreg " Andrew Scull
2020-07-15 18:44 ` [PATCH 27/37] KVM: arm64: nVHE: Unify vgic save and restore Andrew Scull
2020-07-15 18:44 ` [PATCH 28/37] KVM: arm64: nVHE: Unify fpexc32 saving paths Andrew Scull
2020-07-15 18:44 ` [PATCH 29/37] KVM: arm64: nVHE: Separate the save and restore of debug state Andrew Scull
2020-07-15 18:44 ` [PATCH 30/37] KVM: arm64: nVHE: Remove MMU assumption in speculative AT workaround Andrew Scull
2020-07-15 18:44 ` [PATCH 31/37] KVM: arm64: Move speculative AT ISBs into context Andrew Scull
2020-07-15 18:44 ` [PATCH 32/37] KVM: arm64: nVHE: Unify sysreg state restoration paths Andrew Scull
2020-07-15 18:44 ` [PATCH 33/37] KVM: arm64: Remove __activate_vm wrapper Andrew Scull
2020-07-15 18:44 ` [PATCH 34/37] KVM: arm64: nVHE: Unify timer restore paths Andrew Scull
2020-07-15 18:44 ` [PATCH 35/37] KVM: arm64: nVHE: Unify PMU event restoration paths Andrew Scull
2020-07-15 18:44 ` [PATCH 36/37] KVM: arm64: nVHE: Unify GIC PMR " Andrew Scull
2020-07-15 18:44 ` [PATCH 37/37] KVM: arm64: Separate save and restore of vcpu trap state Andrew Scull

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