Re: [PATCH v4 14/21] arm64: Honor VHE being disabled from the command-line
On Sat, 23 Jan 2021 14:07:53 +, Catalin Marinas wrote: > > On Mon, Jan 18, 2021 at 09:45:26AM +, Marc Zyngier wrote: > > diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S > > index 59820f9b8522..bbab2148a2a2 100644 > > --- a/arch/arm64/kernel/hyp-stub.S > > +++ b/arch/arm64/kernel/hyp-stub.S > > @@ -77,13 +77,24 @@ SYM_CODE_END(el1_sync) > > SYM_CODE_START_LOCAL(mutate_to_vhe) > > // Sanity check: MMU *must* be off > > mrs x0, sctlr_el2 > > - tbnzx0, #0, 1f > > + tbnzx0, #0, 2f > > > > // Needs to be VHE capable, obviously > > mrs x0, id_aa64mmfr1_el1 > > ubfxx0, x0, #ID_AA64MMFR1_VHE_SHIFT, #4 > > - cbz x0, 1f > > + cbz x0, 2f > > > > + // Check whether VHE is disabled from the command line > > + adr_l x1, id_aa64mmfr1_val > > + ldr x0, [x1] > > + adr_l x1, id_aa64mmfr1_mask > > + ldr x1, [x1] > > + ubfxx0, x0, #ID_AA64MMFR1_VHE_SHIFT, #4 > > + ubfxx1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4 > > + cbz x1, 1f > > + and x0, x0, x1 > > + cbz x0, 2f > > +1: > > I can see the advantage here in separate id_aa64mmfr1_val/mask but we > could use some asm offsets here and keep the pointer indirection simpler > in C code. You'd just need something like 'adr_l mmfr1_ovrd + VAL_OFFSET'. > > Anyway, if you have a strong preference for the current approach, leave > it as is. I've now moved over to a structure containing both val/mask, meaning that we only need to keep a single pointer around in the various feature descriptors. It certainly looks better. Thanks, M. -- Without deviation from the norm, progress is not possible.
Re: [PATCH v4 14/21] arm64: Honor VHE being disabled from the command-line
On Mon, Jan 18, 2021 at 09:45:26AM +, Marc Zyngier wrote: > diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S > index 59820f9b8522..bbab2148a2a2 100644 > --- a/arch/arm64/kernel/hyp-stub.S > +++ b/arch/arm64/kernel/hyp-stub.S > @@ -77,13 +77,24 @@ SYM_CODE_END(el1_sync) > SYM_CODE_START_LOCAL(mutate_to_vhe) > // Sanity check: MMU *must* be off > mrs x0, sctlr_el2 > - tbnzx0, #0, 1f > + tbnzx0, #0, 2f > > // Needs to be VHE capable, obviously > mrs x0, id_aa64mmfr1_el1 > ubfxx0, x0, #ID_AA64MMFR1_VHE_SHIFT, #4 > - cbz x0, 1f > + cbz x0, 2f > > + // Check whether VHE is disabled from the command line > + adr_l x1, id_aa64mmfr1_val > + ldr x0, [x1] > + adr_l x1, id_aa64mmfr1_mask > + ldr x1, [x1] > + ubfxx0, x0, #ID_AA64MMFR1_VHE_SHIFT, #4 > + ubfxx1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4 > + cbz x1, 1f > + and x0, x0, x1 > + cbz x0, 2f > +1: I can see the advantage here in separate id_aa64mmfr1_val/mask but we could use some asm offsets here and keep the pointer indirection simpler in C code. You'd just need something like 'adr_l mmfr1_ovrd + VAL_OFFSET'. Anyway, if you have a strong preference for the current approach, leave it as is. -- Catalin
Re: [PATCH v4 14/21] arm64: Honor VHE being disabled from the command-line
On Mon, Jan 18, 2021 at 09:45:26AM +, Marc Zyngier wrote: > Finally we can check whether VHE is disabled on the command line, > and not enable it if that's the user's wish. > > Signed-off-by: Marc Zyngier Acked-by: David Brazdil > --- > arch/arm64/kernel/hyp-stub.S | 17 ++--- > 1 file changed, 14 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S > index 59820f9b8522..bbab2148a2a2 100644 > --- a/arch/arm64/kernel/hyp-stub.S > +++ b/arch/arm64/kernel/hyp-stub.S > @@ -77,13 +77,24 @@ SYM_CODE_END(el1_sync) > SYM_CODE_START_LOCAL(mutate_to_vhe) > // Sanity check: MMU *must* be off > mrs x0, sctlr_el2 > - tbnzx0, #0, 1f > + tbnzx0, #0, 2f > > // Needs to be VHE capable, obviously > mrs x0, id_aa64mmfr1_el1 > ubfxx0, x0, #ID_AA64MMFR1_VHE_SHIFT, #4 > - cbz x0, 1f > + cbz x0, 2f > > + // Check whether VHE is disabled from the command line > + adr_l x1, id_aa64mmfr1_val > + ldr x0, [x1] > + adr_l x1, id_aa64mmfr1_mask > + ldr x1, [x1] super nit: There's a ldr_l macro > + ubfxx0, x0, #ID_AA64MMFR1_VHE_SHIFT, #4 > + ubfxx1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4 > + cbz x1, 1f > + and x0, x0, x1 > + cbz x0, 2f > +1: > // Engage the VHE magic! > mov_q x0, HCR_HOST_VHE_FLAGS > msr hcr_el2, x0 > @@ -152,7 +163,7 @@ skip_spe: > orr x0, x0, x1 > msr spsr_el1, x0 > > -1: eret > +2: eret > SYM_CODE_END(mutate_to_vhe) > > .macro invalid_vectorlabel > -- > 2.29.2 >
