linux-kernel - [RFC PATCH 4/6] kvm: arm64: Remove patching of fn pointers in hyp

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Message-Id: <20201119162543.78001-5-dbrazdil@google.com>
Date:   Thu, 19 Nov 2020 16:25:41 +0000
From:   David Brazdil <dbrazdil@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andrew Scull <ascull@...gle.com>,
        Ard Biesheuvel <ardb@...nel.org>, kernel-team@...roid.com,
        David Brazdil <dbrazdil@...gle.com>
Subject: [RFC PATCH 4/6] kvm: arm64: Remove patching of fn pointers in hyp

Taking a function pointer will now generate a R_AARCH64_RELATIVE that is
fixed up at early boot. Remove the alternative-based mechanism for
converting the address from a kernel VA.

Signed-off-by: David Brazdil <dbrazdil@...gle.com>
---
 arch/arm64/include/asm/kvm_mmu.h   | 18 ------------------
 arch/arm64/kernel/image-vars.h     |  1 -
 arch/arm64/kvm/hyp/nvhe/hyp-main.c | 11 ++++-------
 arch/arm64/kvm/va_layout.c         |  6 ------
 4 files changed, 4 insertions(+), 32 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index e5226f7e4732..8cb8974ec9cc 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -121,24 +121,6 @@ static __always_inline unsigned long __kern_hyp_va(unsigned long v)
 
 #define kern_hyp_va(v) 	((typeof(v))(__kern_hyp_va((unsigned long)(v))))
 
-static __always_inline unsigned long __kimg_hyp_va(unsigned long v)
-{
-	unsigned long offset;
-
-	asm volatile(ALTERNATIVE_CB("movz %0, #0\n"
-				    "movk %0, #0, lsl #16\n"
-				    "movk %0, #0, lsl #32\n"
-				    "movk %0, #0, lsl #48\n",
-				    kvm_update_kimg_phys_offset)
-		     : "=r" (offset));
-
-	return __kern_hyp_va((v - offset) | PAGE_OFFSET);
-}
-
-#define kimg_fn_hyp_va(v) 	((typeof(*v))(__kimg_hyp_va((unsigned long)(v))))
-
-#define kimg_fn_ptr(x)	(typeof(x) **)(x)
-
 /*
  * We currently support using a VM-specified IPA size. For backward
  * compatibility, the default IPA size is fixed to 40bits.
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 8539f34d7538..6379721236cf 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -64,7 +64,6 @@ __efistub__ctype		= _ctype;
 /* Alternative callbacks for init-time patching of nVHE hyp code. */
 KVM_NVHE_ALIAS(kvm_patch_vector_branch);
 KVM_NVHE_ALIAS(kvm_update_va_mask);
-KVM_NVHE_ALIAS(kvm_update_kimg_phys_offset);
 KVM_NVHE_ALIAS(kvm_get_kimage_voffset);
 
 /* Global kernel state accessed by nVHE hyp code. */
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index b3db5f4eea27..7998eff5f0a2 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -110,9 +110,9 @@ static void handle___vgic_v3_restore_aprs(struct kvm_cpu_context *host_ctxt)
 
 typedef void (*hcall_t)(struct kvm_cpu_context *);
 
-#define HANDLE_FUNC(x)	[__KVM_HOST_SMCCC_FUNC_##x] = kimg_fn_ptr(handle_##x)
+#define HANDLE_FUNC(x)	[__KVM_HOST_SMCCC_FUNC_##x] = (hcall_t)handle_##x
 
-static const hcall_t *host_hcall[] = {
+static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__kvm_vcpu_run),
 	HANDLE_FUNC(__kvm_flush_vm_context),
 	HANDLE_FUNC(__kvm_tlb_flush_vmid_ipa),
@@ -132,7 +132,6 @@ static const hcall_t *host_hcall[] = {
 static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
 {
 	DECLARE_REG(unsigned long, id, host_ctxt, 0);
-	const hcall_t *kfn;
 	hcall_t hfn;
 
 	id -= KVM_HOST_SMCCC_ID(0);
@@ -140,13 +139,11 @@ static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
 	if (unlikely(id >= ARRAY_SIZE(host_hcall)))
 		goto inval;
 
-	kfn = host_hcall[id];
-	if (unlikely(!kfn))
+	hfn = host_hcall[id];
+	if (unlikely(!hfn))
 		goto inval;
 
 	cpu_reg(host_ctxt, 0) = SMCCC_RET_SUCCESS;
-
-	hfn = kimg_fn_hyp_va(kfn);
 	hfn(host_ctxt);
 
 	return;
diff --git a/arch/arm64/kvm/va_layout.c b/arch/arm64/kvm/va_layout.c
index 7f45a98eacfd..0494315f71f2 100644
--- a/arch/arm64/kvm/va_layout.c
+++ b/arch/arm64/kvm/va_layout.c
@@ -373,12 +373,6 @@ static void generate_mov_q(u64 val, __le32 *origptr, __le32 *updptr, int nr_inst
 	*updptr++ = cpu_to_le32(insn);
 }
 
-void kvm_update_kimg_phys_offset(struct alt_instr *alt,
-				 __le32 *origptr, __le32 *updptr, int nr_inst)
-{
-	generate_mov_q(kimage_voffset + PHYS_OFFSET, origptr, updptr, nr_inst);
-}
-
 void kvm_get_kimage_voffset(struct alt_instr *alt,
 			    __le32 *origptr, __le32 *updptr, int nr_inst)
 {
-- 
2.29.2.299.gdc1121823c-goog