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| Started by | Christoffer Dall <christoffer.dall@linaro.org> |
|---|---|
| First post | 2016-02-01 14:20 +0100 |
| Last post | 2016-02-01 16:40 +0100 |
| Articles | 3 — 2 participants |
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Re: [PATCH v2 05/21] arm64: KVM: VHE: Turn VTCR_EL2 setup into a reusable macro Christoffer Dall <christoffer.dall@linaro.org> - 2016-02-01 14:20 +0100
Re: [PATCH v2 05/21] arm64: KVM: VHE: Turn VTCR_EL2 setup into a reusable macro Marc Zyngier <marc.zyngier@arm.com> - 2016-02-01 15:30 +0100
Re: [PATCH v2 05/21] arm64: KVM: VHE: Turn VTCR_EL2 setup into a reusable macro Christoffer Dall <christoffer.dall@linaro.org> - 2016-02-01 16:40 +0100
| From | Christoffer Dall <christoffer.dall@linaro.org> |
|---|---|
| Date | 2016-02-01 14:20 +0100 |
| Subject | Re: [PATCH v2 05/21] arm64: KVM: VHE: Turn VTCR_EL2 setup into a reusable macro |
| Message-ID | <qXmyD-3iQ-17@gated-at.bofh.it> |
On Mon, Jan 25, 2016 at 03:53:39PM +0000, Marc Zyngier wrote: > On a VHE-capable system, there is no point in setting VTCR_EL2 > at KVM init time. We can perfectly set it up when the kernel > boots, removing the need for a more complicated configuration. what's the complicated configuration which is avoided? > > In order to allow this, turn VTCR_EL2 setup into a macro that > we'll be able to reuse at boot time. > > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> > --- > arch/arm64/include/asm/kvm_mmu.h | 23 +++++++++++++++++++++++ > arch/arm64/kvm/hyp-init.S | 18 +----------------- > 2 files changed, 24 insertions(+), 17 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h > index 7364339..d3e6d7b 100644 > --- a/arch/arm64/include/asm/kvm_mmu.h > +++ b/arch/arm64/include/asm/kvm_mmu.h > @@ -56,6 +56,29 @@ > > #ifdef __ASSEMBLY__ > > +#include <asm/kvm_arm.h> > + > +.macro setup_vtcr tmp1, tmp2 > + mov \tmp1, #(VTCR_EL2_FLAGS & 0xffff) > + movk \tmp1, #(VTCR_EL2_FLAGS >> 16), lsl #16 > + /* > + * Read the PARange bits from ID_AA64MMFR0_EL1 and set the PS bits in > + * VTCR_EL2. > + */ > + mrs \tmp2, id_aa64mmfr0_el1 > + bfi \tmp1, \tmp2, #16, #3 > + /* > + * Read the VMIDBits bits from ID_AA64MMFR1_EL1 and set the VS bit in > + * VTCR_EL2. > + */ > + mrs \tmp2, ID_AA64MMFR1_EL1 > + ubfx \tmp2, \tmp2, #5, #1 > + lsl \tmp2, \tmp2, #VTCR_EL2_VS > + orr \tmp1, \tmp1, \tmp2 > + > + msr vtcr_el2, \tmp1 > + isb > +.endm this feels like an awful lot of code in a header file. Is it crazy to imagine wanting to have different T0SZ for different VMs in the future? In that case, the T0SZ stuff should stay in KVM... Thanks, -Christoffer > /* > * Convert a kernel VA into a HYP VA. > * reg: VA to be converted. > diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S > index 3e568dc..4143e2c 100644 > --- a/arch/arm64/kvm/hyp-init.S > +++ b/arch/arm64/kvm/hyp-init.S > @@ -87,23 +87,7 @@ __do_hyp_init: > #endif > msr tcr_el2, x4 > > - ldr x4, =VTCR_EL2_FLAGS > - /* > - * Read the PARange bits from ID_AA64MMFR0_EL1 and set the PS bits in > - * VTCR_EL2. > - */ > - mrs x5, ID_AA64MMFR0_EL1 > - bfi x4, x5, #16, #3 > - /* > - * Read the VMIDBits bits from ID_AA64MMFR1_EL1 and set the VS bit in > - * VTCR_EL2. > - */ > - mrs x5, ID_AA64MMFR1_EL1 > - ubfx x5, x5, #5, #1 > - lsl x5, x5, #VTCR_EL2_VS > - orr x4, x4, x5 > - > - msr vtcr_el2, x4 > + setup_vtcr x4, x5 > > mrs x4, mair_el1 > msr mair_el2, x4 > -- > 2.1.4 >
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| From | Marc Zyngier <marc.zyngier@arm.com> |
|---|---|
| Date | 2016-02-01 15:30 +0100 |
| Message-ID | <qXnEq-45e-89@gated-at.bofh.it> |
| In reply to | #1323095 |
On 01/02/16 13:13, Christoffer Dall wrote: > On Mon, Jan 25, 2016 at 03:53:39PM +0000, Marc Zyngier wrote: >> On a VHE-capable system, there is no point in setting VTCR_EL2 >> at KVM init time. We can perfectly set it up when the kernel >> boots, removing the need for a more complicated configuration. > > what's the complicated configuration which is avoided? With VHE, there is no hyp-init at all, so what we avoid is a weird init sequence where we have to execute part of this hyp-init, but not all of it. >> >> In order to allow this, turn VTCR_EL2 setup into a macro that >> we'll be able to reuse at boot time. >> >> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> >> --- >> arch/arm64/include/asm/kvm_mmu.h | 23 +++++++++++++++++++++++ >> arch/arm64/kvm/hyp-init.S | 18 +----------------- >> 2 files changed, 24 insertions(+), 17 deletions(-) >> >> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h >> index 7364339..d3e6d7b 100644 >> --- a/arch/arm64/include/asm/kvm_mmu.h >> +++ b/arch/arm64/include/asm/kvm_mmu.h >> @@ -56,6 +56,29 @@ >> >> #ifdef __ASSEMBLY__ >> >> +#include <asm/kvm_arm.h> >> + >> +.macro setup_vtcr tmp1, tmp2 >> + mov \tmp1, #(VTCR_EL2_FLAGS & 0xffff) >> + movk \tmp1, #(VTCR_EL2_FLAGS >> 16), lsl #16 >> + /* >> + * Read the PARange bits from ID_AA64MMFR0_EL1 and set the PS bits in >> + * VTCR_EL2. >> + */ >> + mrs \tmp2, id_aa64mmfr0_el1 >> + bfi \tmp1, \tmp2, #16, #3 >> + /* >> + * Read the VMIDBits bits from ID_AA64MMFR1_EL1 and set the VS bit in >> + * VTCR_EL2. >> + */ >> + mrs \tmp2, ID_AA64MMFR1_EL1 >> + ubfx \tmp2, \tmp2, #5, #1 >> + lsl \tmp2, \tmp2, #VTCR_EL2_VS >> + orr \tmp1, \tmp1, \tmp2 >> + >> + msr vtcr_el2, \tmp1 >> + isb >> +.endm > > this feels like an awful lot of code in a header file. interrupt_head.S respectfully disagrees with you ;-). > Is it crazy to imagine wanting to have different T0SZ for different VMs > in the future? In that case, the T0SZ stuff should stay in KVM... That's a rather compelling argument indeed. I'll see if I can turn the thing around in a slightly nicer way. How about moving it out of hyp-init.S altogether, and into C code? Thanks, M. -- Jazz is not dead. It just smells funny...
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| From | Christoffer Dall <christoffer.dall@linaro.org> |
|---|---|
| Date | 2016-02-01 16:40 +0100 |
| Message-ID | <qXoK7-4Sy-37@gated-at.bofh.it> |
| In reply to | #1323172 |
On Mon, Feb 01, 2016 at 02:21:57PM +0000, Marc Zyngier wrote: > On 01/02/16 13:13, Christoffer Dall wrote: > > On Mon, Jan 25, 2016 at 03:53:39PM +0000, Marc Zyngier wrote: > >> On a VHE-capable system, there is no point in setting VTCR_EL2 > >> at KVM init time. We can perfectly set it up when the kernel > >> boots, removing the need for a more complicated configuration. > > > > what's the complicated configuration which is avoided? > > With VHE, there is no hyp-init at all, so what we avoid is a weird init > sequence where we have to execute part of this hyp-init, but not all of it. > > >> > >> In order to allow this, turn VTCR_EL2 setup into a macro that > >> we'll be able to reuse at boot time. > >> > >> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> > >> --- > >> arch/arm64/include/asm/kvm_mmu.h | 23 +++++++++++++++++++++++ > >> arch/arm64/kvm/hyp-init.S | 18 +----------------- > >> 2 files changed, 24 insertions(+), 17 deletions(-) > >> > >> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h > >> index 7364339..d3e6d7b 100644 > >> --- a/arch/arm64/include/asm/kvm_mmu.h > >> +++ b/arch/arm64/include/asm/kvm_mmu.h > >> @@ -56,6 +56,29 @@ > >> > >> #ifdef __ASSEMBLY__ > >> > >> +#include <asm/kvm_arm.h> > >> + > >> +.macro setup_vtcr tmp1, tmp2 > >> + mov \tmp1, #(VTCR_EL2_FLAGS & 0xffff) > >> + movk \tmp1, #(VTCR_EL2_FLAGS >> 16), lsl #16 > >> + /* > >> + * Read the PARange bits from ID_AA64MMFR0_EL1 and set the PS bits in > >> + * VTCR_EL2. > >> + */ > >> + mrs \tmp2, id_aa64mmfr0_el1 > >> + bfi \tmp1, \tmp2, #16, #3 > >> + /* > >> + * Read the VMIDBits bits from ID_AA64MMFR1_EL1 and set the VS bit in > >> + * VTCR_EL2. > >> + */ > >> + mrs \tmp2, ID_AA64MMFR1_EL1 > >> + ubfx \tmp2, \tmp2, #5, #1 > >> + lsl \tmp2, \tmp2, #VTCR_EL2_VS > >> + orr \tmp1, \tmp1, \tmp2 > >> + > >> + msr vtcr_el2, \tmp1 > >> + isb > >> +.endm > > > > this feels like an awful lot of code in a header file. > > interrupt_head.S respectfully disagrees with you ;-). > > > Is it crazy to imagine wanting to have different T0SZ for different VMs > > in the future? In that case, the T0SZ stuff should stay in KVM... > > That's a rather compelling argument indeed. I'll see if I can turn the > thing around in a slightly nicer way. How about moving it out of > hyp-init.S altogether, and into C code? That sounds better to me. Thanks, -Christoffer
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