[PATCH v3 17/18] KVM: arm64: nVHE: Migrate hyp-init to SMCCC
Andrew Scull
ascull at google.com
Thu Sep 3 09:53:06 EDT 2020
To complete the transition to SMCCC, the hyp initialization is given a
function ID. This looks neater than comparing the hyp stub function IDs
to the page table physical address.
Some care is taken to only clobber x0-3 before the host context is saved
as only those registers can be clobbered accoring to SMCCC. Fortunately,
only a few acrobatics are needed. The possible new tpidr_el2 is moved to
the argument in x2 so that it can be stashed in tpidr_el2 early to free
up a scratch register. The page table configuration then makes use of
x0-2.
Signed-off-by: Andrew Scull <ascull at google.com>
---
arch/arm64/include/asm/kvm_host.h | 5 ---
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/arm.c | 5 ++-
arch/arm64/kvm/hyp.S | 22 ----------
arch/arm64/kvm/hyp/nvhe/hyp-init.S | 66 +++++++++++++++++-------------
5 files changed, 43 insertions(+), 57 deletions(-)
delete mode 100644 arch/arm64/kvm/hyp.S
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 82c941cf8890..ef0325c42ca0 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -480,11 +480,6 @@ int kvm_test_age_hva(struct kvm *kvm, unsigned long hva);
void kvm_arm_halt_guest(struct kvm *kvm);
void kvm_arm_resume_guest(struct kvm *kvm);
-u64 __kvm_call_hyp_init(phys_addr_t pgd_ptr,
- unsigned long hyp_stack_ptr,
- unsigned long vector_ptr,
- unsigned long tpidr_el2);
-
#define kvm_call_hyp_nvhe(f, ...) \
({ \
struct arm_smccc_res res; \
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 99977c1972cc..1504c81fbf5d 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -13,7 +13,7 @@ obj-$(CONFIG_KVM) += hyp/
kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
$(KVM)/vfio.o $(KVM)/irqchip.o \
arm.o mmu.o mmio.o psci.o perf.o hypercalls.o pvtime.o \
- inject_fault.o regmap.o va_layout.o hyp.o handle_exit.o \
+ inject_fault.o regmap.o va_layout.o handle_exit.o \
guest.o debug.o reset.o sys_regs.o \
vgic-sys-reg-v3.o fpsimd.o pmu.o \
aarch32.o arch_timer.o \
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 49aa08bd26de..c074d9824d54 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1264,6 +1264,7 @@ static void cpu_init_hyp_mode(void)
unsigned long hyp_stack_ptr;
unsigned long vector_ptr;
unsigned long tpidr_el2;
+ struct arm_smccc_res res;
/* Switch from the HYP stub to our own HYP init vector */
__hyp_set_vectors(kvm_get_idmap_vector());
@@ -1288,7 +1289,9 @@ static void cpu_init_hyp_mode(void)
* cpus_have_const_cap() wrapper.
*/
BUG_ON(!system_capabilities_finalized());
- __kvm_call_hyp_init(pgd_ptr, hyp_stack_ptr, vector_ptr, tpidr_el2);
+ arm_smccc_1_1_hvc(KVM_HOST_SMCCC_FUNC(__kvm_hyp_init),
+ pgd_ptr, tpidr_el2, hyp_stack_ptr, vector_ptr, &res);
+ WARN_ON(res.a0 != SMCCC_RET_SUCCESS);
/*
* Disabling SSBD on a non-VHE system requires us to enable SSBS
diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
deleted file mode 100644
index 12aa426f7559..000000000000
--- a/arch/arm64/kvm/hyp.S
+++ /dev/null
@@ -1,22 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Copyright (C) 2012,2013 - ARM Ltd
- * Author: Marc Zyngier <marc.zyngier at arm.com>
- */
-
-#include <linux/linkage.h>
-
-#include <asm/alternative.h>
-#include <asm/assembler.h>
-#include <asm/cpufeature.h>
-
-/*
- * u64 __kvm_call_hyp_init(phys_addr_t pgd_ptr,
- * unsigned long hyp_stack_ptr,
- * unsigned long vector_ptr,
- * unsigned long tpidr_el2);
- */
-SYM_FUNC_START(__kvm_call_hyp_init)
- hvc #0
- ret
-SYM_FUNC_END(__kvm_call_hyp_init)
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index abe885e26fe2..47224dc62c51 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -4,11 +4,13 @@
* Author: Marc Zyngier <marc.zyngier at arm.com>
*/
+#include <linux/arm-smccc.h>
#include <linux/linkage.h>
#include <asm/alternative.h>
#include <asm/assembler.h>
#include <asm/kvm_arm.h>
+#include <asm/kvm_asm.h>
#include <asm/kvm_mmu.h>
#include <asm/pgtable-hwdef.h>
#include <asm/sysreg.h>
@@ -44,27 +46,37 @@ __invalid:
b .
/*
- * x0: HYP pgd
- * x1: HYP stack
- * x2: HYP vectors
- * x3: per-CPU offset
+ * x0: SMCCC function ID
+ * x1: HYP pgd
+ * x2: per-CPU offset
+ * x3: HYP stack
+ * x4: HYP vectors
*/
__do_hyp_init:
/* Check for a stub HVC call */
cmp x0, #HVC_STUB_HCALL_NR
b.lo __kvm_handle_stub_hvc
- phys_to_ttbr x4, x0
+ /* Set tpidr_el2 for use by HYP to free a register */
+ msr tpidr_el2, x2
+
+ mov x2, #KVM_HOST_SMCCC_FUNC(__kvm_hyp_init)
+ cmp x0, x2
+ b.eq 1f
+ mov x0, #SMCCC_RET_NOT_SUPPORTED
+ eret
+
+1: phys_to_ttbr x0, x1
alternative_if ARM64_HAS_CNP
- orr x4, x4, #TTBR_CNP_BIT
+ orr x0, x0, #TTBR_CNP_BIT
alternative_else_nop_endif
- msr ttbr0_el2, x4
+ msr ttbr0_el2, x0
- mrs x4, tcr_el1
- mov_q x5, TCR_EL2_MASK
- and x4, x4, x5
- mov x5, #TCR_EL2_RES1
- orr x4, x4, x5
+ mrs x0, tcr_el1
+ mov_q x1, TCR_EL2_MASK
+ and x0, x0, x1
+ mov x1, #TCR_EL2_RES1
+ orr x0, x0, x1
/*
* The ID map may be configured to use an extended virtual address
@@ -80,18 +92,18 @@ alternative_else_nop_endif
*
* So use the same T0SZ value we use for the ID map.
*/
- ldr_l x5, idmap_t0sz
- bfi x4, x5, TCR_T0SZ_OFFSET, TCR_TxSZ_WIDTH
+ ldr_l x1, idmap_t0sz
+ bfi x0, x1, TCR_T0SZ_OFFSET, TCR_TxSZ_WIDTH
/*
* Set the PS bits in TCR_EL2.
*/
- tcr_compute_pa_size x4, #TCR_EL2_PS_SHIFT, x5, x6
+ tcr_compute_pa_size x0, #TCR_EL2_PS_SHIFT, x1, x2
- msr tcr_el2, x4
+ msr tcr_el2, x0
- mrs x4, mair_el1
- msr mair_el2, x4
+ mrs x0, mair_el1
+ msr mair_el2, x0
isb
/* Invalidate the stale TLBs from Bootloader */
@@ -103,24 +115,22 @@ alternative_else_nop_endif
* as well as the EE bit on BE. Drop the A flag since the compiler
* is allowed to generate unaligned accesses.
*/
- mov_q x4, (SCTLR_EL2_RES1 | (SCTLR_ELx_FLAGS & ~SCTLR_ELx_A))
-CPU_BE( orr x4, x4, #SCTLR_ELx_EE)
+ mov_q x0, (SCTLR_EL2_RES1 | (SCTLR_ELx_FLAGS & ~SCTLR_ELx_A))
+CPU_BE( orr x0, x0, #SCTLR_ELx_EE)
alternative_if ARM64_HAS_ADDRESS_AUTH
- mov_q x5, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \
+ mov_q x1, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \
SCTLR_ELx_ENDA | SCTLR_ELx_ENDB)
- orr x4, x4, x5
+ orr x0, x0, x1
alternative_else_nop_endif
- msr sctlr_el2, x4
+ msr sctlr_el2, x0
isb
/* Set the stack and new vectors */
- mov sp, x1
- msr vbar_el2, x2
-
- /* Set tpidr_el2 for use by HYP */
- msr tpidr_el2, x3
+ mov sp, x3
+ msr vbar_el2, x4
/* Hello, World! */
+ mov x0, #SMCCC_RET_SUCCESS
eret
SYM_CODE_END(__kvm_hyp_init)
--
2.28.0.402.g5ffc5be6b7-goog
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