From: marc.zyngier@arm.com (Marc Zyngier)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 2/2] arm: KVM: keep arm vfp/simd exit handling consistent with arm64
Date: Fri, 19 Jun 2015 14:50:33 +0100 [thread overview]
Message-ID: <55841E29.7070004@arm.com> (raw)
In-Reply-To: <55835910.3060601@samsung.com>
On 19/06/15 00:49, Mario Smarduch wrote:
> On 06/18/2015 10:27 AM, Marc Zyngier wrote:
>> On 16/06/15 22:50, Mario Smarduch wrote:
>>> After enhancing arm64 FP/SIMD exit handling, FP/SIMD exit branch is moved
>>> to guest trap handling. This keeps exiting handling flow between both
>>> architectures consistent.
>>>
>>> Signed-off-by: Mario Smarduch <m.smarduch@samsung.com>
>>> ---
>>> arch/arm/kvm/interrupts.S | 12 +++++++-----
>>> 1 file changed, 7 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
>>> index 79caf79..fca2c56 100644
>>> --- a/arch/arm/kvm/interrupts.S
>>> +++ b/arch/arm/kvm/interrupts.S
>>> @@ -363,10 +363,6 @@ hyp_hvc:
>>> @ Check syndrome register
>>> mrc p15, 4, r1, c5, c2, 0 @ HSR
>>> lsr r0, r1, #HSR_EC_SHIFT
>>> -#ifdef CONFIG_VFPv3
>>> - cmp r0, #HSR_EC_CP_0_13
>>> - beq switch_to_guest_vfp
>>> -#endif
>>> cmp r0, #HSR_EC_HVC
>>> bne guest_trap @ Not HVC instr.
>>>
>>> @@ -406,6 +402,12 @@ THUMB( orr lr, #1)
>>> 1: eret
>>>
>>> guest_trap:
>>> +#ifdef CONFIG_VFPv3
>>> + /* Guest accessed VFP/SIMD registers, save host, restore Guest */
>>> + cmp r0, #HSR_EC_CP_0_13
>>> + beq switch_to_guest_fpsimd
>>> +#endif
>>> +
>>> load_vcpu @ Load VCPU pointer to r0
>>> str r1, [vcpu, #VCPU_HSR]
>>>
>>> @@ -478,7 +480,7 @@ guest_trap:
>>> * inject an undefined exception to the guest.
>>> */
>>> #ifdef CONFIG_VFPv3
>>> -switch_to_guest_vfp:
>>> +switch_to_guest_fpsimd:
>>
>> Ah, I think I managed to confuse you in my previous comment.
>> On ARMv7, we call the floating point stuff VFP.
>> On ARMv8, we call it FP/SIMD.
>
> Ah I see, I'll update.
>>
>> Not very consistent, I know...
>>
>>> load_vcpu @ Load VCPU pointer to r0
>
> How about move it here - then it does not stick out like
> before.
>
> guest_trap:
> load_vcpu @ Load VCPU pointer to r0
> str r1, [vcpu, #VCPU_HSR]
>
> @ Check if we need the fault information
> lsr r1, r1, #HSR_EC_SHIFT
> #ifdef CONFIG_VFPv3
> /* Guest accessed VFP/SIMD registers, save host, restore Guest */
> cmp r1, #HSR_EC_CP_0_13
> beq switch_to_guest_vfp
> #endif
That would work.
> Regarding "host_switch_to_hyp:" it has no reference but appears
> like a clean separator, that's on purpose?
Not really. It looks like a leftover from the original HYP calling
method that we used to have, before the code got merged.
You could replace it by a simple comment saying that from this point on,
we're dealing with a HVC call from the host.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <marc.zyngier@arm.com>
To: Mario Smarduch <m.smarduch@samsung.com>
Cc: "kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
"christoffer.dall@linaro.org" <christoffer.dall@linaro.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Will Deacon <Will.Deacon@arm.com>
Subject: Re: [PATCH v2 2/2] arm: KVM: keep arm vfp/simd exit handling consistent with arm64
Date: Fri, 19 Jun 2015 14:50:33 +0100 [thread overview]
Message-ID: <55841E29.7070004@arm.com> (raw)
In-Reply-To: <55835910.3060601@samsung.com>
On 19/06/15 00:49, Mario Smarduch wrote:
> On 06/18/2015 10:27 AM, Marc Zyngier wrote:
>> On 16/06/15 22:50, Mario Smarduch wrote:
>>> After enhancing arm64 FP/SIMD exit handling, FP/SIMD exit branch is moved
>>> to guest trap handling. This keeps exiting handling flow between both
>>> architectures consistent.
>>>
>>> Signed-off-by: Mario Smarduch <m.smarduch@samsung.com>
>>> ---
>>> arch/arm/kvm/interrupts.S | 12 +++++++-----
>>> 1 file changed, 7 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S
>>> index 79caf79..fca2c56 100644
>>> --- a/arch/arm/kvm/interrupts.S
>>> +++ b/arch/arm/kvm/interrupts.S
>>> @@ -363,10 +363,6 @@ hyp_hvc:
>>> @ Check syndrome register
>>> mrc p15, 4, r1, c5, c2, 0 @ HSR
>>> lsr r0, r1, #HSR_EC_SHIFT
>>> -#ifdef CONFIG_VFPv3
>>> - cmp r0, #HSR_EC_CP_0_13
>>> - beq switch_to_guest_vfp
>>> -#endif
>>> cmp r0, #HSR_EC_HVC
>>> bne guest_trap @ Not HVC instr.
>>>
>>> @@ -406,6 +402,12 @@ THUMB( orr lr, #1)
>>> 1: eret
>>>
>>> guest_trap:
>>> +#ifdef CONFIG_VFPv3
>>> + /* Guest accessed VFP/SIMD registers, save host, restore Guest */
>>> + cmp r0, #HSR_EC_CP_0_13
>>> + beq switch_to_guest_fpsimd
>>> +#endif
>>> +
>>> load_vcpu @ Load VCPU pointer to r0
>>> str r1, [vcpu, #VCPU_HSR]
>>>
>>> @@ -478,7 +480,7 @@ guest_trap:
>>> * inject an undefined exception to the guest.
>>> */
>>> #ifdef CONFIG_VFPv3
>>> -switch_to_guest_vfp:
>>> +switch_to_guest_fpsimd:
>>
>> Ah, I think I managed to confuse you in my previous comment.
>> On ARMv7, we call the floating point stuff VFP.
>> On ARMv8, we call it FP/SIMD.
>
> Ah I see, I'll update.
>>
>> Not very consistent, I know...
>>
>>> load_vcpu @ Load VCPU pointer to r0
>
> How about move it here - then it does not stick out like
> before.
>
> guest_trap:
> load_vcpu @ Load VCPU pointer to r0
> str r1, [vcpu, #VCPU_HSR]
>
> @ Check if we need the fault information
> lsr r1, r1, #HSR_EC_SHIFT
> #ifdef CONFIG_VFPv3
> /* Guest accessed VFP/SIMD registers, save host, restore Guest */
> cmp r1, #HSR_EC_CP_0_13
> beq switch_to_guest_vfp
> #endif
That would work.
> Regarding "host_switch_to_hyp:" it has no reference but appears
> like a clean separator, that's on purpose?
Not really. It looks like a leftover from the original HYP calling
method that we used to have, before the code got merged.
You could replace it by a simple comment saying that from this point on,
we're dealing with a HVC call from the host.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
next prev parent reply other threads:[~2015-06-19 13:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-16 21:50 [PATCH v2 0/2] arm/arm64: KVM: Optimize arm64 fp/simd, saves 30-50% on exits Mario Smarduch
2015-06-16 21:50 ` Mario Smarduch
2015-06-16 21:50 ` [PATCH v2 1/2] arm64: KVM: Optimize arm64 fp/simd save/restore Mario Smarduch
2015-06-16 21:50 ` Mario Smarduch
2015-06-18 17:04 ` Marc Zyngier
2015-06-18 17:04 ` Marc Zyngier
2015-06-16 21:50 ` [PATCH v2 2/2] arm: KVM: keep arm vfp/simd exit handling consistent with arm64 Mario Smarduch
2015-06-16 21:50 ` Mario Smarduch
2015-06-18 17:27 ` Marc Zyngier
2015-06-18 17:27 ` Marc Zyngier
2015-06-18 23:49 ` Mario Smarduch
2015-06-18 23:49 ` Mario Smarduch
2015-06-19 13:50 ` Marc Zyngier [this message]
2015-06-19 13:50 ` Marc Zyngier
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