Re: [PATCH v13 03/18] arm64: hyp-stub: Move el1_sync into the vectors

On Thu, 08 Apr 2021 15:45:18 +0100,
Pavel Tatashin [off-list ref] wrote:

On Thu, Apr 8, 2021 at 6:24 AM Marc Zyngier [off-list ref] wrote:

quoted

On 2021-04-08 05:05, Pavel Tatashin wrote:

quoted

From: James Morse <james.morse@arm.com>

The hyp-stub's el1_sync code doesn't do very much, this can easily fit
in the vectors.

With this, all of the hyp-stubs behaviour is contained in its vectors.
This lets kexec and hibernate copy the hyp-stub when they need its
behaviour, instead of re-implementing it.

Signed-off-by: James Morse <james.morse@arm.com>

[Fixed merging issues]

That's a pretty odd fix IMO.

quoted

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
---
 arch/arm64/kernel/hyp-stub.S | 59 ++++++++++++++++++------------------
 1 file changed, 29 insertions(+), 30 deletions(-)

diff --git a/arch/arm64/kernel/hyp-stub.S

b/arch/arm64/kernel/hyp-stub.S
index ff329c5c074d..d1a73d0f74e0 100644

--- a/arch/arm64/kernel/hyp-stub.S
+++ b/arch/arm64/kernel/hyp-stub.S

@@ -21,6 +21,34 @@ SYM_CODE_START_LOCAL(\label)
      .align 7
      b       \label
 SYM_CODE_END(\label)
+.endm
+
+.macro hyp_stub_el1_sync
+SYM_CODE_START_LOCAL(hyp_stub_el1_sync)
+     .align 7
+     cmp     x0, #HVC_SET_VECTORS
+     b.ne    2f
+     msr     vbar_el2, x1
+     b       9f
+
+2:   cmp     x0, #HVC_SOFT_RESTART
+     b.ne    3f
+     mov     x0, x2
+     mov     x2, x4
+     mov     x4, x1
+     mov     x1, x3
+     br      x4                              // no return
+
+3:   cmp     x0, #HVC_RESET_VECTORS
+     beq     9f                              // Nothing to reset!
+
+     /* Someone called kvm_call_hyp() against the hyp-stub... */
+     mov_q   x0, HVC_STUB_ERR
+     eret
+
+9:   mov     x0, xzr
+     eret
+SYM_CODE_END(hyp_stub_el1_sync)

You said you tested this on a TX2. I guess you don't care whether
it runs VHE or not...

Hi Marc,

Thank you for noticing this. Not sure how this missmerge happened. I
have added the missing case, and VHE is initialized correctly during
boot.
[   14.698175] kvm [1]: VHE mode initialized successfully

During normal boot, kexec reboot, and kdump reboot. I will respin the
series and send the version 14 soon.

Please give people a chance to review this lot first. This isn't code
that is easy to digest, and immediate re-spinning does more harm than
good (this isn't targeting 5.13, I would assume).

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

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