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Date: Mon, 31 Aug 2015 20:49:17 +0200 From: Christoffer Dall <christoffer.dall@...aro.org> To: Marc Zyngier <marc.zyngier@....com> Cc: Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu Subject: Re: [PATCH 12/13] arm64: KVM: Split sysreg save/restore On Wed, Jul 08, 2015 at 05:19:15PM +0100, Marc Zyngier wrote: > As we're starting to get different requirements for non-VHE and VHE > code paths, use a slightly more fine-grained approach: > > - __save/restore_sysregs: save/restore non-shared sysregs > - __save/restore_shared_sysregs: save/restore only shared sysregs > > Of course, non-VHE always requires both. > I'm sorry, I don't really understand what this patch does. What is a 'shared sysreg' exactly? One that is shared between the host and the guest? Or one that is shared between EL1 and EL2? Or is that the same thing? > Signed-off-by: Marc Zyngier <marc.zyngier@....com> > --- > arch/arm64/kvm/hyp.S | 91 +++++++++++++++++++++++++--------------------------- > 1 file changed, 44 insertions(+), 47 deletions(-) > > diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S > index b61591b..3cbd2c4 100644 > --- a/arch/arm64/kvm/hyp.S > +++ b/arch/arm64/kvm/hyp.S > @@ -280,11 +280,6 @@ skip_el1_restore: > mrs x20, par_el1 > mrs x21, mdscr_el1 > > - mrs x22, tpidr_el0 > - mrs x23, tpidrro_el0 > - mrs x24, tpidr_el1 > - mrs x25, actlr_el1 > - > stp x4, x5, [x3] > stp x6, x7, [x3, #16] > stp x8, x9, [x3, #32] > @@ -294,8 +289,6 @@ skip_el1_restore: > stp x16, x17, [x3, #96] > stp x18, x19, [x3, #112] > stp x20, x21, [x3, #128] > - stp x22, x23, [x3, #144] > - stp x24, x25, [x3, #160] > .endm > > .macro save_debug > @@ -508,8 +501,6 @@ skip_el1_restore: > ldp x16, x17, [x3, #96] > ldp x18, x19, [x3, #112] > ldp x20, x21, [x3, #128] > - ldp x22, x23, [x3, #144] > - ldp x24, x25, [x3, #160] > > msr vmpidr_el2, x4 > msr csselr_el1, x5 > @@ -529,11 +520,6 @@ skip_el1_restore: > msr_el1(cntkctl, x19) > msr par_el1, x20 > msr mdscr_el1, x21 > - > - msr tpidr_el0, x22 > - msr tpidrro_el0, x23 > - msr tpidr_el1, x24 > - msr actlr_el1, x25 > .endm > > .macro restore_debug > @@ -913,10 +899,12 @@ ifnvhe nop, "msr vbar_el1, x2" > > .macro save_timer_state > // x0: vcpu pointer > - ldr x2, [x0, #VCPU_KVM] > - kern_hyp_va x2 > - ldr w3, [x2, #KVM_TIMER_ENABLED] > - cbz w3, 1f > + // x1: return code > + // x2: vcpu context > + ldr x3, [x0, #VCPU_KVM] > + kern_hyp_va x3 > + ldr w4, [x3, #KVM_TIMER_ENABLED] > + cbz w4, 1f > > mrs_el0(x3, cntv_ctl) > and x3, x3, #3 > @@ -931,9 +919,9 @@ ifnvhe nop, "msr vbar_el1, x2" > > 1: > // Allow physical timer/counter access for the host > - mrs x2, cnthctl_el2 > - orr x2, x2, #3 > - msr cnthctl_el2, x2 > + mrs x3, cnthctl_el2 > + orr x3, x3, #3 > + msr cnthctl_el2, x3 > > // Clear cntvoff for the host > ifnvhe "msr cntvoff_el2, xzr", nop > @@ -941,34 +929,43 @@ ifnvhe "msr cntvoff_el2, xzr", nop > > .macro restore_timer_state > // x0: vcpu pointer > + // x2: vcpu context > // Disallow physical timer access for the guest > // Physical counter access is allowed > - mrs x2, cnthctl_el2 > - orr x2, x2, #1 > - bic x2, x2, #2 > - msr cnthctl_el2, x2 > - > - ldr x2, [x0, #VCPU_KVM] > - kern_hyp_va x2 > - ldr w3, [x2, #KVM_TIMER_ENABLED] > - cbz w3, 1f > - > - ldr x3, [x2, #KVM_TIMER_CNTVOFF] > - msr cntvoff_el2, x3 > - ldr x2, [x0, #VCPU_TIMER_CNTV_CVAL] > - msr_el0(cntv_cval, x2) > + mrs x3, cnthctl_el2 > + orr x3, x3, #1 > + bic x3, x3, #2 > + msr cnthctl_el2, x3 > + > + ldr x3, [x0, #VCPU_KVM] > + kern_hyp_va x3 > + ldr w4, [x3, #KVM_TIMER_ENABLED] > + cbz w4, 1f > + > + ldr x4, [x3, #KVM_TIMER_CNTVOFF] > + msr cntvoff_el2, x4 > + ldr x4, [x0, #VCPU_TIMER_CNTV_CVAL] > + msr_el0(cntv_cval, x4) > isb > > - ldr w2, [x0, #VCPU_TIMER_CNTV_CTL] > - and x2, x2, #3 > - msr_el0(cntv_ctl, x2) > + ldr w4, [x0, #VCPU_TIMER_CNTV_CTL] > + and x4, x4, #3 > + msr_el0(cntv_ctl, x4) > 1: > .endm > > +__save_shared_sysregs: > + save_shared_sysregs > + ret > + > __save_sysregs: > save_sysregs > ret > > +__restore_shared_sysregs: > + restore_shared_sysregs > + ret > + > __restore_sysregs: > restore_sysregs > ret > @@ -1010,10 +1007,9 @@ ENTRY(__kvm_vcpu_run) > > save_host_regs > bl __save_fpsimd > -ifnvhe "bl __save_sysregs", nop > -ifnvhe "b 1f", nop > - save_shared_sysregs > -1: > +ifnvhe "bl __save_sysregs", "nop" > + bl __save_shared_sysregs > + > compute_debug_state 1f > bl __save_debug > 1: > @@ -1027,6 +1023,7 @@ ifnvhe "b 1f", nop > add x2, x0, #VCPU_CONTEXT > > bl __restore_sysregs > + bl __restore_shared_sysregs > bl __restore_fpsimd > > skip_debug_state x3, 1f > @@ -1048,6 +1045,7 @@ __kvm_vcpu_return: > save_guest_regs > bl __save_fpsimd > bl __save_sysregs > + bl __save_shared_sysregs > > skip_debug_state x3, 1f > bl __save_debug > @@ -1064,10 +1062,8 @@ __kvm_vcpu_return: > ldr x2, [x0, #VCPU_HOST_CONTEXT] > kern_hyp_va x2 > > -ifnvhe "bl __restore_sysregs", nop > -ifnvhe "b 1f", nop > - restore_shared_sysregs > -1: > +ifnvhe "bl __restore_sysregs", "nop" > + bl __restore_shared_sysregs > bl __restore_fpsimd > > skip_debug_state x3, 1f > @@ -1159,7 +1155,8 @@ __kvm_hyp_panic: > ldr x2, [x0, #VCPU_HOST_CONTEXT] > kern_hyp_va x2 > > - bl __restore_sysregs > +ifnvhe "bl __restore_sysregs", "nop" > + bl __restore_shared_sysregs > > 1: adr x0, __hyp_panic_str > adr x1, 2f > -- > 2.1.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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