linux-kernel - [PATCH v4 09/26] kvm: arm64: Remove vector

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Message-Id: <20201202184122.26046-10-dbrazdil@google.com>
Date:   Wed,  2 Dec 2020 18:41:05 +0000
From:   David Brazdil <dbrazdil@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     Jonathan Corbet <corbet@....net>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Sudeep Holla <sudeep.holla@....com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kernel-team@...roid.com, David Brazdil <dbrazdil@...gle.com>
Subject: [PATCH v4 09/26] kvm: arm64: Remove vector_ptr param of hyp-init

KVM precomputes the hyp VA of __kvm_hyp_host_vector, essentially a
constant (minus ASLR), before passing it to __kvm_hyp_init.
Now that we have alternatives for converting kimg VA to hyp VA, replace
this with computing the constant inside __kvm_hyp_init, thus removing
the need for an argument.

Signed-off-by: David Brazdil <dbrazdil@...gle.com>
---
 arch/arm64/include/asm/kvm_asm.h   |  2 --
 arch/arm64/include/asm/kvm_mmu.h   | 24 ++++++++++++++++++++++++
 arch/arm64/kvm/arm.c               |  4 +---
 arch/arm64/kvm/hyp/nvhe/hyp-init.S |  9 ++++++---
 4 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 4a6a77d8d13e..531f9d04eefd 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -163,10 +163,8 @@ struct kvm_vcpu;
 struct kvm_s2_mmu;
 
 DECLARE_KVM_NVHE_SYM(__kvm_hyp_init);
-DECLARE_KVM_NVHE_SYM(__kvm_hyp_host_vector);
 DECLARE_KVM_HYP_SYM(__kvm_hyp_vector);
 #define __kvm_hyp_init		CHOOSE_NVHE_SYM(__kvm_hyp_init)
-#define __kvm_hyp_host_vector	CHOOSE_NVHE_SYM(__kvm_hyp_host_vector)
 #define __kvm_hyp_vector	CHOOSE_HYP_SYM(__kvm_hyp_vector)
 
 extern unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index e298191a854d..e52d82aeadca 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -94,6 +94,30 @@ alternative_cb_end
 	sub	\reg, \reg, \tmp
 .endm
 
+/*
+ * Convert a kernel image address to a hyp VA
+ * reg: kernel address to be converted in place
+ * tmp: temporary register
+ *
+ * The actual code generation takes place in kvm_get_kimage_voffset, and
+ * the instructions below are only there to reserve the space and
+ * perform the register allocation (kvm_update_kimg_phys_offset uses the
+ * specific registers encoded in the instructions).
+ */
+.macro kimg_hyp_va reg, tmp
+alternative_cb kvm_update_kimg_phys_offset
+	movz	\tmp, #0
+	movk	\tmp, #0, lsl #16
+	movk	\tmp, #0, lsl #32
+	movk	\tmp, #0, lsl #48
+alternative_cb_end
+
+	sub	\reg, \reg, \tmp
+	mov_q	\tmp, PAGE_OFFSET
+	orr	\reg, \reg, \tmp
+	kern_hyp_va \reg
+.endm
+
 #else
 
 #include <linux/pgtable.h>
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index d9e8d7dc7e11..9e5d0ea84822 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1386,7 +1386,6 @@ static void cpu_init_hyp_mode(void)
 {
 	phys_addr_t pgd_ptr;
 	unsigned long hyp_stack_ptr;
-	unsigned long vector_ptr;
 	unsigned long tpidr_el2;
 	struct arm_smccc_res res;
 
@@ -1404,7 +1403,6 @@ static void cpu_init_hyp_mode(void)
 	pgd_ptr = kvm_mmu_get_httbr();
 	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)kern_hyp_va(kvm_ksym_ref(__kvm_hyp_host_vector));
 
 	/*
 	 * Call initialization code, and switch to the full blown HYP code.
@@ -1414,7 +1412,7 @@ static void cpu_init_hyp_mode(void)
 	 */
 	BUG_ON(!system_capabilities_finalized());
 	arm_smccc_1_1_hvc(KVM_HOST_SMCCC_FUNC(__kvm_hyp_init),
-			  pgd_ptr, tpidr_el2, hyp_stack_ptr, vector_ptr, &res);
+			  pgd_ptr, tpidr_el2, hyp_stack_ptr, &res);
 	WARN_ON(res.a0 != SMCCC_RET_SUCCESS);
 
 	/*
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index b11a9d7db677..931a8c38f085 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -50,7 +50,6 @@ __invalid:
 	 * x1: HYP pgd
 	 * x2: per-CPU offset
 	 * x3: HYP stack
-	 * x4: HYP vectors
 	 */
 __do_hyp_init:
 	/* Check for a stub HVC call */
@@ -134,9 +133,13 @@ alternative_else_nop_endif
 	msr	sctlr_el2, x0
 	isb
 
-	/* Set the stack and new vectors */
+	/* Set the stack */
 	mov	sp, x3
-	msr	vbar_el2, x4
+
+	/* Set the host vector */
+	ldr	x0, =__kvm_hyp_host_vector
+	kimg_hyp_va x0, x1
+	msr	vbar_el2, x0
 
 	/* Hello, World! */
 	mov	x0, #SMCCC_RET_SUCCESS
-- 
2.29.2.454.gaff20da3a2-goog