Re: [PATCH v3 04/21] arm64: Provide an 'upgrade to VHE' stub hypercall
From: Marc Zyngier <maz@kernel.org>
Date: 2021-01-11 13:54:16
Also in:
kvmarm, lkml
On 2021-01-11 13:27, Marc Zyngier wrote:
As we are about to change the way a VHE system boots, let's provide the core helper, in the form of a stub hypercall that enables VHE and replicates the full EL1 context at EL2, thanks to EL1 and VHE-EL2 being extremely similar. On exception return, the kernel carries on at EL2. Fancy! Nothing calls this new hypercall yet, so no functional change.
Famous last words...
quoted hunk ↗ jump to hunk
Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/include/asm/virt.h | 7 +++- arch/arm64/kernel/hyp-stub.S | 67 +++++++++++++++++++++++++++++++++-- 2 files changed, 71 insertions(+), 3 deletions(-)diff --git a/arch/arm64/include/asm/virt.hb/arch/arm64/include/asm/virt.h index ee6a48df89d9..7379f35ae2c6 100644--- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h@@ -35,8 +35,13 @@ */ #define HVC_RESET_VECTORS 2 +/* + * HVC_VHE_RESTART - Upgrade the CPU from EL1 to EL2, if possible + */ +#define HVC_VHE_RESTART 3 + /* Max number of HYP stub hypercalls */ -#define HVC_STUB_HCALL_NR 3 +#define HVC_STUB_HCALL_NR 4 /* Error returned when an invalid stub number is passed into x0 */ #define HVC_STUB_ERR 0xbadca11diff --git a/arch/arm64/kernel/hyp-stub.Sb/arch/arm64/kernel/hyp-stub.S index 160f5881a0b7..0a84602344eb 100644--- a/arch/arm64/kernel/hyp-stub.S +++ b/arch/arm64/kernel/hyp-stub.S@@ -8,9 +8,9 @@ #include <linux/init.h> #include <linux/linkage.h> -#include <linux/irqchip/arm-gic-v3.h> #include <asm/assembler.h> +#include <asm/el2_setup.h> #include <asm/kvm_arm.h> #include <asm/kvm_asm.h> #include <asm/ptrace.h>@@ -47,10 +47,13 @@ SYM_CODE_END(__hyp_stub_vectors) SYM_CODE_START_LOCAL(el1_sync) cmp x0, #HVC_SET_VECTORS - b.ne 2f + b.ne 1f msr vbar_el2, x1 b 9f +1: cmp x0, #HVC_VHE_RESTART + b mutate_to_vhe
And of course, I managed to send the *wrong* version of this patch.
This should obviously be a "b.eq", otherwise none of the other
hypercalls are reachable...
The correct version of this is now pushed in my tree[1].
Thanks,
M.
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=hack/arm64-early-cpufeature
--
Jazz is not dead. It just smells funny...
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