For the KVM and XEN hypervisors to be usable, we need to enter the
kernel in HYP mode. Now that we already are in non-secure state,
HYP mode switching is within short reach.
While doing the non-secure switch, we have to enable the HVC
instruction and setup the HYP mode HVBAR (while still secure).
The actual switch is done by dropping back from a HYP mode handler
without actually leaving HYP mode, so we introduce a new handler
routine in the exception vector table.
In the assembly switching routine - which we rename to hyp_gic_switch
on the way - we save and restore the banked LR and SP registers
around the hypercall to do the actual HYP mode switch.
The C routine first checks whether we are in HYP mode already and
also whether the virtualization extensions are available. It also
checks whether the HYP mode switch was finally successful.
The bootm command part only adds and adjusts some error reporting.
Signed-off-by: Andre Przywara <andre.przyw...@linaro.org>
---
arch/arm/cpu/armv7/start.S | 34 +++++++++++++++++++++++-----------
arch/arm/include/asm/armv7.h | 4 ++--
arch/arm/lib/bootm.c | 12 +++++++++---
arch/arm/lib/virt-v7.c | 22 +++++++++++++++-------
4 files changed, 49 insertions(+), 23 deletions(-)
diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 02234c7..921e9d9 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -41,7 +41,7 @@ _start: b reset
ldr pc, _software_interrupt
ldr pc, _prefetch_abort
ldr pc, _data_abort
- ldr pc, _not_used
+ ldr pc, _hyp_trap
ldr pc, _irq
ldr pc, _fiq
#ifdef CONFIG_SPL_BUILD
@@ -49,7 +49,7 @@ _undefined_instruction: .word _undefined_instruction
_software_interrupt: .word _software_interrupt
_prefetch_abort: .word _prefetch_abort
_data_abort: .word _data_abort
-_not_used: .word _not_used
+_hyp_trap: .word _hyp_trap
_irq: .word _irq
_fiq: .word _fiq
_pad: .word 0x12345678 /* now 16*4=64 */
@@ -58,7 +58,7 @@ _undefined_instruction: .word undefined_instruction
_software_interrupt: .word software_interrupt
_prefetch_abort: .word prefetch_abort
_data_abort: .word data_abort
-_not_used: .word not_used
+_hyp_trap: .word hyp_trap
_irq: .word irq
_fiq: .word fiq
_pad: .word 0x12345678 /* now 16*4=64 */
@@ -513,12 +513,18 @@ software_interrupt:
mrc p15, 0, r1, c1, c1, 0 @ read SCR
bic r1, r1, #0x07f
orr r1, r1, #0x31 @ enable NS, AW, FW
+ mrc p15, 0, r0, c0, c1, 1 @ check for Virt ext
+ and r0, r0, #0xf000
+ cmp r0, #0x1000
+ orreq r1, r1, #0x100 @ allow HVC instruction
mrc p15, 0, r0, c12, c0, 0 @ save secure copy of VBAR
mcr p15, 0, r1, c1, c1, 0 @ write SCR, switch to non-sec
isb
mcr p15, 0, r0, c12, c0, 0 @ write non-secure copy of VBAR
+ mcreq p15, 4, r0, c12, c0, 0 @ write HYP mode HVBAR
+
movs pc, lr
.align 5
@@ -534,10 +540,9 @@ data_abort:
bl do_data_abort
.align 5
-not_used:
- get_bad_stack
- bad_save_user_regs
- bl do_not_used
+hyp_trap:
+ .byte 0x00, 0xe3, 0x0e, 0xe1 @ mrs lr, elr_hyp
+ mov pc, lr
#ifdef CONFIG_USE_IRQ
@@ -574,21 +579,21 @@ fiq:
#endif /* CONFIG_SPL_BUILD */
#ifdef CONFIG_ARMV7_VIRT
-/* Routine to initialize GIC CPU interface and switch to nonsecure state.
- * Will be executed directly by secondary CPUs after coming out of
+/* Routine to initialize GIC CPU interface, switch to nonsecure and to HYP
+ * mode. Will be executed directly by secondary CPUs after coming out of
* WFI, or can be called directly by C code for CPU 0.
* Those two paths mandate to not use any stack and to only use registers
* r0-r3 to comply with both the C ABI and the requirement of SMP startup
* code.
*/
-.globl _nonsec_gic_switch
+.globl _hyp_gic_switch
.globl _smp_pen
_smp_pen:
mrs r0, cpsr
orr r0, r0, #0xc0
msr cpsr, r0 @ disable interrupts
mov lr, #0 @ clear LR to mark secondary
-_nonsec_gic_switch:
+_hyp_gic_switch:
mrc p15, 4, r2, c15, c0, 0 @ r2 = PERIPHBASE
add r3, r2, #0x1000 @ GIC dist i/f offset
mvn r1, #0
@@ -628,6 +633,13 @@ _nonsec_gic_switch:
add r2, r2, #0x1000 @ GIC dist i/f offset
str r1, [r2] @ allow private interrupts
+ mov r2, lr
+ mov r1, sp
+ .byte 0x70, 0x00, 0x40, 0xe1 @ hvc #0
+ isb
+ mov sp, r1
+ mov lr, r2
+
cmp lr, #0
movne pc, lr @ CPU 0 to return
@ all others: go to sleep
diff --git a/arch/arm/include/asm/armv7.h b/arch/arm/include/asm/armv7.h
index 296dc92..17bb497 100644
--- a/arch/arm/include/asm/armv7.h
+++ b/arch/arm/include/asm/armv7.h
@@ -75,11 +75,11 @@ void v7_outer_cache_flush_range(u32 start, u32 end);
void v7_outer_cache_inval_range(u32 start, u32 end);
#ifdef CONFIG_ARMV7_VIRT
-int armv7_switch_nonsec(void);
+int armv7_switch_hyp(void);
/* defined in cpu/armv7/start.S */
void _smp_pen(void);
-void _nonsec_gic_switch(void);
+void _hyp_gic_switch(void);
#endif /* CONFIG_ARMV7_VIRT */
#endif
diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
index a3d3aae..552ba59 100644
--- a/arch/arm/lib/bootm.c
+++ b/arch/arm/lib/bootm.c
@@ -324,12 +324,15 @@ static void boot_prep_linux(bootm_headers_t *images)
#endif /* all tags */
}
#ifdef CONFIG_ARMV7_VIRT
- switch (armv7_switch_nonsec()) {
+ switch (armv7_switch_hyp()) {
case 0:
- debug("entered non-secure state\n");
+ debug("entered HYP mode\n");
+ break;
+ case 1:
+ debug("CPU already in HYP mode\n");
break;
case 2:
- printf("HYP mode: Security extensions not implemented.\n");
+ printf("HYP mode: Virtualization extensions not
implemented.\n");
break;
case 3:
printf("HYP mode: CPU not supported (must be Cortex-A15 or
A7).\n");
@@ -337,6 +340,9 @@ static void boot_prep_linux(bootm_headers_t *images)
case 4:
printf("HYP mode: PERIPHBASE is above 4 GB, cannot access
this.\n");
break;
+ case 5:
+ printf("HYP mode: switch not successful.\n");
+ break;
}
#endif
}
diff --git a/arch/arm/lib/virt-v7.c b/arch/arm/lib/virt-v7.c
index 0248010..3883463 100644
--- a/arch/arm/lib/virt-v7.c
+++ b/arch/arm/lib/virt-v7.c
@@ -3,6 +3,7 @@
* Andre Przywara, Linaro
*
* routines to push ARMv7 processors from secure into non-secure state
+ * and from non-secure SVC into HYP mode
* needed to enable ARMv7 virtualization for current hypervisors
*
* See file CREDITS for list of people who contributed to this
@@ -43,16 +44,20 @@ static inline unsigned int read_cpsr(void)
return reg;
}
-int armv7_switch_nonsec(void)
+int armv7_switch_hyp(void)
{
unsigned int reg;
volatile unsigned int *gicdptr;
unsigned itlinesnr, i;
unsigned int *sysflags;
- /* check whether the CPU supports the security extensions */
+ /* check whether we are in HYP mode already */
+ if ((read_cpsr() & 0x1F) == 0x1a)
+ return 1;
+
+ /* check whether the CPU supports the virtualization extensions */
asm("mrc p15, 0, %0, c0, c1, 1\n" : "=r"(reg));
- if ((reg & 0xF0) == 0)
+ if ((reg & 0xF000) != 0x1000)
return 2;
/* the timer frequency for the generic timer needs to be
@@ -73,8 +78,8 @@ int armv7_switch_nonsec(void)
*/
/* check whether we are an Cortex-A15 or A7.
- * The actual non-secure switch should work with all CPUs supporting
- * the security extension, but we need the GIC address,
+ * The actual HYP switch should work with all CPUs supporting
+ * the virtualization extension, but we need the GIC address,
* which we know only for sure for those two CPUs.
*/
asm("mrc p15, 0, %0, c0, c0, 0\n" : "=r"(reg));
@@ -113,8 +118,11 @@ int armv7_switch_nonsec(void)
sysflags[0] = (uintptr_t)_smp_pen;
gicdptr[GICD_SGIR / 4] = 1U << 24;
- /* call the non-sec switching code on this CPU also */
- _nonsec_gic_switch();
+ /* call the HYP switching code on this CPU also */
+ _hyp_gic_switch();
+
+ if ((read_cpsr() & 0x1F) != 0x1a)
+ return 5;
return 0;
}
--
1.7.12.1
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