diff mbox

[v3,18/41] KVM: arm64: Move userspace system registers into separate function

Message ID 20180112120747.27999-19-christoffer.dall@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Christoffer Dall Jan. 12, 2018, 12:07 p.m. UTC 
There's a semantic difference between the EL1 registers that control
operation of a kernel running in EL1 and EL1 registers that only control
userspace execution in EL0.  Since we can defer saving/restoring the
latter, move them into their own function.

We also take this chance to rename the function saving/restoring the
remaining system register to make it clear this function deals with
the EL1 system registers.

No functional change.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 arch/arm64/kvm/hyp/sysreg-sr.c | 46 +++++++++++++++++++++++++++++++-----------
 1 file changed, 34 insertions(+), 12 deletions(-)

Comments

Julien Grall Feb. 9, 2018, 6:50 p.m. UTC | #1 
Hi Christoffer,

On 01/12/2018 12:07 PM, Christoffer Dall wrote:
> There's a semantic difference between the EL1 registers that control
> operation of a kernel running in EL1 and EL1 registers that only control
> userspace execution in EL0.  Since we can defer saving/restoring the
> latter, move them into their own function.
> 
> We also take this chance to rename the function saving/restoring the
> remaining system register to make it clear this function deals with
> the EL1 system registers.
> 
> No functional change.
> 
> Reviewed-by: Andrew Jones <drjones@redhat.com>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
>   arch/arm64/kvm/hyp/sysreg-sr.c | 46 +++++++++++++++++++++++++++++++-----------
>   1 file changed, 34 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
> index 848a46eb33bf..99dd50ce483b 100644
> --- a/arch/arm64/kvm/hyp/sysreg-sr.c
> +++ b/arch/arm64/kvm/hyp/sysreg-sr.c
> @@ -34,18 +34,27 @@ static void __hyp_text __sysreg_do_nothing(struct kvm_cpu_context *ctxt) { }
>   
>   static void __hyp_text __sysreg_save_common_state(struct kvm_cpu_context *ctxt)
>   {
> -	ctxt->sys_regs[ACTLR_EL1]	= read_sysreg(actlr_el1);

I am a bit confused, the comment on top of the function says the host 
must save ACTLR_EL1 in the VHE case. But AFAICT, after this patch the 
register will not get saved in the host context. Did I miss anything?

Cheers,
Christoffer Dall Feb. 14, 2018, 11:22 a.m. UTC | #2 
On Fri, Feb 09, 2018 at 06:50:14PM +0000, Julien Grall wrote:
> Hi Christoffer,
> 
> On 01/12/2018 12:07 PM, Christoffer Dall wrote:
> >There's a semantic difference between the EL1 registers that control
> >operation of a kernel running in EL1 and EL1 registers that only control
> >userspace execution in EL0.  Since we can defer saving/restoring the
> >latter, move them into their own function.
> >
> >We also take this chance to rename the function saving/restoring the
> >remaining system register to make it clear this function deals with
> >the EL1 system registers.
> >
> >No functional change.
> >
> >Reviewed-by: Andrew Jones <drjones@redhat.com>
> >Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> >---
> >  arch/arm64/kvm/hyp/sysreg-sr.c | 46 +++++++++++++++++++++++++++++++-----------
> >  1 file changed, 34 insertions(+), 12 deletions(-)
> >
> >diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
> >index 848a46eb33bf..99dd50ce483b 100644
> >--- a/arch/arm64/kvm/hyp/sysreg-sr.c
> >+++ b/arch/arm64/kvm/hyp/sysreg-sr.c
> >@@ -34,18 +34,27 @@ static void __hyp_text __sysreg_do_nothing(struct kvm_cpu_context *ctxt) { }
> >  static void __hyp_text __sysreg_save_common_state(struct kvm_cpu_context *ctxt)
> >  {
> >-	ctxt->sys_regs[ACTLR_EL1]	= read_sysreg(actlr_el1);
> 
> I am a bit confused, the comment on top of the function says the host must
> save ACTLR_EL1 in the VHE case. But AFAICT, after this patch the register
> will not get saved in the host context. Did I miss anything?
> 
You're right, there is indeed a functional change here, introduced in
v2.

I have adjusted the commentary and the patch description.

Thanks,
-Christoffer
diff mbox

Patch

diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
index 848a46eb33bf..99dd50ce483b 100644
--- a/arch/arm64/kvm/hyp/sysreg-sr.c
+++ b/arch/arm64/kvm/hyp/sysreg-sr.c
@@ -34,18 +34,27 @@  static void __hyp_text __sysreg_do_nothing(struct kvm_cpu_context *ctxt) { }
 
 static void __hyp_text __sysreg_save_common_state(struct kvm_cpu_context *ctxt)
 {
-	ctxt->sys_regs[ACTLR_EL1]	= read_sysreg(actlr_el1);
-	ctxt->sys_regs[TPIDR_EL0]	= read_sysreg(tpidr_el0);
-	ctxt->sys_regs[TPIDRRO_EL0]	= read_sysreg(tpidrro_el0);
 	ctxt->sys_regs[MDSCR_EL1]	= read_sysreg(mdscr_el1);
+
+	/*
+	 * The host arm64 Linux uses sp_el0 to point to 'current' and it must
+	 * therefore be saved/restored on every entry/exit to/from the guest.
+	 */
 	ctxt->gp_regs.regs.sp		= read_sysreg(sp_el0);
 }
 
-static void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)
+static void __hyp_text __sysreg_save_user_state(struct kvm_cpu_context *ctxt)
+{
+	ctxt->sys_regs[TPIDR_EL0]	= read_sysreg(tpidr_el0);
+	ctxt->sys_regs[TPIDRRO_EL0]	= read_sysreg(tpidrro_el0);
+}
+
+static void __hyp_text __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
 {
 	ctxt->sys_regs[MPIDR_EL1]	= read_sysreg(vmpidr_el2);
 	ctxt->sys_regs[CSSELR_EL1]	= read_sysreg(csselr_el1);
 	ctxt->sys_regs[SCTLR_EL1]	= read_sysreg_el1(sctlr);
+	ctxt->sys_regs[ACTLR_EL1]	= read_sysreg(actlr_el1);
 	ctxt->sys_regs[CPACR_EL1]	= read_sysreg_el1(cpacr);
 	ctxt->sys_regs[TTBR0_EL1]	= read_sysreg_el1(ttbr0);
 	ctxt->sys_regs[TTBR1_EL1]	= read_sysreg_el1(ttbr1);
@@ -70,35 +79,46 @@  static void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)
 }
 
 static hyp_alternate_select(__sysreg_call_save_host_state,
-			    __sysreg_save_state, __sysreg_do_nothing,
+			    __sysreg_save_el1_state, __sysreg_do_nothing,
 			    ARM64_HAS_VIRT_HOST_EXTN);
 
 void __hyp_text __sysreg_save_host_state(struct kvm_cpu_context *ctxt)
 {
 	__sysreg_call_save_host_state()(ctxt);
 	__sysreg_save_common_state(ctxt);
+	__sysreg_save_user_state(ctxt);
 }
 
 void __hyp_text __sysreg_save_guest_state(struct kvm_cpu_context *ctxt)
 {
-	__sysreg_save_state(ctxt);
+	__sysreg_save_el1_state(ctxt);
 	__sysreg_save_common_state(ctxt);
+	__sysreg_save_user_state(ctxt);
 }
 
 static void __hyp_text __sysreg_restore_common_state(struct kvm_cpu_context *ctxt)
 {
-	write_sysreg(ctxt->sys_regs[ACTLR_EL1],	  actlr_el1);
-	write_sysreg(ctxt->sys_regs[TPIDR_EL0],	  tpidr_el0);
-	write_sysreg(ctxt->sys_regs[TPIDRRO_EL0], tpidrro_el0);
 	write_sysreg(ctxt->sys_regs[MDSCR_EL1],	  mdscr_el1);
+
+	/*
+	 * The host arm64 Linux uses sp_el0 to point to 'current' and it must
+	 * therefore be saved/restored on every entry/exit to/from the guest.
+	 */
 	write_sysreg(ctxt->gp_regs.regs.sp,	  sp_el0);
 }
 
-static void __hyp_text __sysreg_restore_state(struct kvm_cpu_context *ctxt)
+static void __hyp_text __sysreg_restore_user_state(struct kvm_cpu_context *ctxt)
+{
+	write_sysreg(ctxt->sys_regs[TPIDR_EL0],	  	tpidr_el0);
+	write_sysreg(ctxt->sys_regs[TPIDRRO_EL0], 	tpidrro_el0);
+}
+
+static void __hyp_text __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt)
 {
 	write_sysreg(ctxt->sys_regs[MPIDR_EL1],		vmpidr_el2);
 	write_sysreg(ctxt->sys_regs[CSSELR_EL1],	csselr_el1);
 	write_sysreg_el1(ctxt->sys_regs[SCTLR_EL1],	sctlr);
+	write_sysreg(ctxt->sys_regs[ACTLR_EL1],	  	actlr_el1);
 	write_sysreg_el1(ctxt->sys_regs[CPACR_EL1],	cpacr);
 	write_sysreg_el1(ctxt->sys_regs[TTBR0_EL1],	ttbr0);
 	write_sysreg_el1(ctxt->sys_regs[TTBR1_EL1],	ttbr1);
@@ -123,19 +143,21 @@  static void __hyp_text __sysreg_restore_state(struct kvm_cpu_context *ctxt)
 }
 
 static hyp_alternate_select(__sysreg_call_restore_host_state,
-			    __sysreg_restore_state, __sysreg_do_nothing,
+			    __sysreg_restore_el1_state, __sysreg_do_nothing,
 			    ARM64_HAS_VIRT_HOST_EXTN);
 
 void __hyp_text __sysreg_restore_host_state(struct kvm_cpu_context *ctxt)
 {
 	__sysreg_call_restore_host_state()(ctxt);
 	__sysreg_restore_common_state(ctxt);
+	__sysreg_restore_user_state(ctxt);
 }
 
 void __hyp_text __sysreg_restore_guest_state(struct kvm_cpu_context *ctxt)
 {
-	__sysreg_restore_state(ctxt);
+	__sysreg_restore_el1_state(ctxt);
 	__sysreg_restore_common_state(ctxt);
+	__sysreg_restore_user_state(ctxt);
 }
 
 static void __hyp_text __fpsimd32_save_state(struct kvm_cpu_context *ctxt)