From 9da5ac236de6ab2189c999eb9ddddeef1431ab68 Mon Sep 17 00:00:00 2001 From: Russell King Date: Mon, 3 Apr 2017 19:37:46 +0100 Subject: ARM: soft-reboot into same mode that we entered the kernel When we soft-reboot (eg, kexec) from one kernel into the next, we need to ensure that we enter the new kernel in the same processor mode as when we were entered, so that (eg) the new kernel can install its own hypervisor - the old kernel's hypervisor will have been overwritten. In order to do this, we need to pass a flag to cpu_reset() so it knows what to do, and we need to modify the kernel's own hypervisor stub to allow it to handle a soft-reboot. As we are always guaranteed to install our own hypervisor if we're entered in HYP32 mode, and KVM will have moved itself out of the way on kexec/normal reboot, we can assume that our hypervisor is in place when we want to kexec, so changing our hypervisor API should not be a problem. Tested-by: Keerthy Acked-by: Catalin Marinas Signed-off-by: Russell King Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall --- arch/arm/mm/proc-v7.S | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'arch/arm/mm') diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index d00d52c9de3e..1846ca4255d0 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -53,11 +53,15 @@ ENDPROC(cpu_v7_proc_fin) .align 5 .pushsection .idmap.text, "ax" ENTRY(cpu_v7_reset) - mrc p15, 0, r1, c1, c0, 0 @ ctrl register - bic r1, r1, #0x1 @ ...............m - THUMB( bic r1, r1, #1 << 30 ) @ SCTLR.TE (Thumb exceptions) - mcr p15, 0, r1, c1, c0, 0 @ disable MMU + mrc p15, 0, r2, c1, c0, 0 @ ctrl register + bic r2, r2, #0x1 @ ...............m + THUMB( bic r2, r2, #1 << 30 ) @ SCTLR.TE (Thumb exceptions) + mcr p15, 0, r2, c1, c0, 0 @ disable MMU isb +#ifdef CONFIG_ARM_VIRT_EXT + teq r1, #0 + bne __hyp_soft_restart +#endif bx r0 ENDPROC(cpu_v7_reset) .popsection -- cgit v1.2.3 From 6b85677c38510e09d482a9bd57000a099003a898 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 3 Apr 2017 19:37:48 +0100 Subject: ARM: Update cpu_v7_reset documentation cpu_v7_reset() now takes a second parameter indicating whether we should reboot in HYP or not. Update the documentation to reflect this. Tested-by: Keerthy Acked-by: Russell King Acked-by: Catalin Marinas Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall --- arch/arm/mm/proc-v7.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/arm/mm') diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index 1846ca4255d0..01d64c0b2563 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -39,13 +39,14 @@ ENTRY(cpu_v7_proc_fin) ENDPROC(cpu_v7_proc_fin) /* - * cpu_v7_reset(loc) + * cpu_v7_reset(loc, hyp) * * Perform a soft reset of the system. Put the CPU into the * same state as it would be if it had been reset, and branch * to what would be the reset vector. * * - loc - location to jump to for soft reset + * - hyp - indicate if restart occurs in HYP mode * * This code must be executed using a flat identity mapping with * caches disabled. -- cgit v1.2.3 From cf763e4ede9deca45c83d7a59c8e798c4d079da2 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 3 Apr 2017 19:37:50 +0100 Subject: ARM: Expose the VA/IDMAP offset The KVM code needs to be able to compute the address of symbols in its idmap page (the equivalent of a virt_to_idmap() call). Unfortunately, virt_to_idmap is slightly complicated, depending on the use of arch_phys_to_idmap_offset or not, and none of that is readily available at HYP. Instead, expose a single kimage_voffset variable which contains the offset between a kernel VA and its idmap address, enabling the VA->IDMAP conversion. This allows the KVM code to behave similarily to its arm64 counterpart. Tested-by: Keerthy Acked-by: Russell King Acked-by: Catalin Marinas Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall --- arch/arm/mm/mmu.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/arm/mm') diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 4e016d7f37b3..e98a2b5c4e85 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -87,6 +87,8 @@ struct cachepolicy { #define s2_policy(policy) 0 #endif +unsigned long kimage_voffset __ro_after_init; + static struct cachepolicy cache_policies[] __initdata = { { .policy = "uncached", @@ -1635,4 +1637,7 @@ void __init paging_init(const struct machine_desc *mdesc) empty_zero_page = virt_to_page(zero_page); __flush_dcache_page(NULL, empty_zero_page); + + /* Compute the virt/idmap offset, mostly for the sake of KVM */ + kimage_voffset = (unsigned long)&kimage_voffset - virt_to_idmap(&kimage_voffset); } -- cgit v1.2.3