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...
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
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.h
b/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 0xbadca11
diff --git a/arch/arm64/kernel/hyp-stub.S
b/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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