From: Amit Daniel Kachhap <amit.kachhap@arm.com>
To: James Morse <james.morse@arm.com>, linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Andrew Jones <drjones@redhat.com>,
Julien Thierry <julien.thierry@arm.com>,
Marc Zyngier <marc.zyngier@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Christoffer Dall <christoffer.dall@arm.com>,
Kristina Martsenko <kristina.martsenko@arm.com>,
kvmarm@lists.cs.columbia.edu,
Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
Dave Martin <Dave.Martin@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 4/6] arm64/kvm: add a userspace option to enable pointer authentication
Date: Mon, 4 Mar 2019 16:26:34 +0530 [thread overview]
Message-ID: <4e485492-50ef-3162-af3c-7af80b4a17cc@arm.com> (raw)
In-Reply-To: <f7e4156e-c9aa-0356-d9a4-6b01ff23c5c0@arm.com>
Hi James,
On 2/27/19 12:03 AM, James Morse wrote:
> Hi Amit,
>
> On 19/02/2019 09:24, Amit Daniel Kachhap wrote:
>> This feature will allow the KVM guest to allow the handling of
>> pointer authentication instructions or to treat them as undefined
>> if not set. It uses the existing vcpu API KVM_ARM_VCPU_INIT to
>> supply this parameter instead of creating a new API.
>>
>> A new register is not created to pass this parameter via
>> SET/GET_ONE_REG interface as just a flag (KVM_ARM_VCPU_PTRAUTH)
>> supplied is enough to enable this feature.
>
> and an attempt to restore the id register with the other version would fail.
>
>
>> diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt
>> index a25cd21..0529a7d 100644
>> --- a/Documentation/arm64/pointer-authentication.txt
>> +++ b/Documentation/arm64/pointer-authentication.txt
>> @@ -82,7 +82,8 @@ pointers).
>> Virtualization
>> --------------
>>
>> -Pointer authentication is not currently supported in KVM guests. KVM
>> -will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of
>> -the feature will result in an UNDEFINED exception being injected into
>> -the guest.
>
>> +Pointer authentication is enabled in KVM guest when virtual machine is
>> +created by passing a flag (KVM_ARM_VCPU_PTRAUTH)
>
> (This is still mixing VM and VCPU)
>
>
>> + requesting this feature to be enabled.
>
> .. on each vcpu?
>
>
>> +Without this flag, pointer authentication is not enabled
>> +in KVM guests and attempted use of the feature will result in an UNDEFINED
>> +exception being injected into the guest.
>
> 'guests' here suggests its a VM property. If you set it on some VCPU but not others KVM
> will generate undefs instead of enabling the feature. (which is the right thing to do)
>
> I think it needs to be clear this is a per-vcpu property.
ok.
>
>
>> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
>> index 97c3478..5f82ca1 100644
>> --- a/arch/arm64/include/uapi/asm/kvm.h
>> +++ b/arch/arm64/include/uapi/asm/kvm.h
>> @@ -102,6 +102,7 @@ struct kvm_regs {
>> #define KVM_ARM_VCPU_EL1_32BIT 1 /* CPU running a 32bit VM */
>> #define KVM_ARM_VCPU_PSCI_0_2 2 /* CPU uses PSCI v0.2 */
>> #define KVM_ARM_VCPU_PMU_V3 3 /* Support guest PMUv3 */
>
>> +#define KVM_ARM_VCPU_PTRAUTH 4 /* VCPU uses address authentication */
>
> Just address authentication? I agree with Mark we should have two bits to match what gets
> exposed to EL0. One would then be address, the other generic.
ok.
>
>
>> diff --git a/arch/arm64/kvm/hyp/ptrauth-sr.c b/arch/arm64/kvm/hyp/ptrauth-sr.c
>> index 528ee6e..6846a23 100644
>> --- a/arch/arm64/kvm/hyp/ptrauth-sr.c
>> +++ b/arch/arm64/kvm/hyp/ptrauth-sr.c
>> @@ -93,9 +93,23 @@ void kvm_arm_vcpu_ptrauth_reset(struct kvm_vcpu *vcpu)
>
>> +/**
>> + * kvm_arm_vcpu_ptrauth_allowed - checks if ptrauth feature is allowed by user
>> + *
>> + * @vcpu: The VCPU pointer
>> + *
>> + * This function will be used to check userspace option to have ptrauth or not
>> + * in the guest kernel.
>> + */
>> +bool kvm_arm_vcpu_ptrauth_allowed(const struct kvm_vcpu *vcpu)
>> +{
>> + return kvm_supports_ptrauth() &&
>> + test_bit(KVM_ARM_VCPU_PTRAUTH, vcpu->arch.features);
>> +}
>
> This isn't used from world-switch, could it be moved to guest.c?
yes sure.
>
>
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index 12529df..f7bcc60 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -1055,7 +1055,7 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
>> }
>>
>> /* Read a sanitised cpufeature ID register by sys_reg_desc */
>> -static u64 read_id_reg(struct sys_reg_desc const *r, bool raz)
>> +static u64 read_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_desc const *r, bool raz)
>
> (It might be easier on the reviewer to move these mechanical changes to an earlier patch)
Yes with including some of Dave SVE patches this wont be required.
Thanks,
Amit D
>
>
> Looks good,
>
> Thanks,
>
> James
>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-03-04 10:56 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-19 9:24 [PATCH v6 0/6] Add ARMv8.3 pointer authentication for kvm guest Amit Daniel Kachhap
2019-02-19 9:24 ` [PATCH v6 1/6] arm64/kvm: preserve host HCR_EL2 value Amit Daniel Kachhap
2019-02-21 11:50 ` Mark Rutland
2019-02-25 18:09 ` Marc Zyngier
2019-02-28 6:43 ` Amit Daniel Kachhap
2019-02-21 15:49 ` Dave Martin
2019-03-01 5:56 ` Amit Daniel Kachhap
2019-02-25 17:39 ` James Morse
2019-02-26 10:06 ` James Morse
2019-03-02 11:09 ` Amit Daniel Kachhap
2019-02-19 9:24 ` [PATCH v6 2/6] arm64/kvm: preserve host MDCR_EL2 value Amit Daniel Kachhap
2019-02-21 11:57 ` Mark Rutland
2019-02-21 15:51 ` Dave Martin
2019-03-01 6:10 ` Amit Daniel Kachhap
2019-02-19 9:24 ` [PATCH v6 3/6] arm64/kvm: context-switch ptrauth registers Amit Daniel Kachhap
2019-02-21 12:29 ` Mark Rutland
2019-02-21 15:51 ` Dave Martin
2019-03-01 6:17 ` Amit Daniel Kachhap
2019-02-28 9:07 ` Amit Daniel Kachhap
2019-02-21 15:53 ` Dave Martin
2019-03-01 9:35 ` Amit Daniel Kachhap
2019-02-26 18:31 ` James Morse
2019-03-04 10:51 ` Amit Daniel Kachhap
2019-02-19 9:24 ` [PATCH v6 4/6] arm64/kvm: add a userspace option to enable pointer authentication Amit Daniel Kachhap
2019-02-21 12:34 ` Mark Rutland
2019-02-28 9:25 ` Amit Daniel Kachhap
2019-02-21 15:53 ` Dave Martin
2019-03-01 9:41 ` Amit Daniel Kachhap
2019-03-01 12:22 ` Dave P Martin
2019-02-26 18:33 ` James Morse
2019-03-04 10:56 ` Amit Daniel Kachhap [this message]
2019-02-19 9:24 ` [PATCH v6 5/6] arm64/kvm: control accessibility of ptrauth key registers Amit Daniel Kachhap
2019-02-21 15:53 ` Dave Martin
2019-02-26 18:34 ` James Morse
2019-02-19 9:24 ` [kvmtool PATCH v6 6/6] arm/kvm: arm64: Add a vcpu feature for pointer authentication Amit Daniel Kachhap
2019-02-21 15:54 ` Dave Martin
2019-03-01 10:37 ` Amit Daniel Kachhap
2019-03-01 11:24 ` Dave P Martin
2019-03-04 11:08 ` Amit Daniel Kachhap
2019-03-05 11:11 ` Dave Martin
2019-02-26 18:03 ` [PATCH v6 0/6] Add ARMv8.3 pointer authentication for kvm guest James Morse
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4e485492-50ef-3162-af3c-7af80b4a17cc@arm.com \
--to=amit.kachhap@arm.com \
--cc=Dave.Martin@arm.com \
--cc=catalin.marinas@arm.com \
--cc=christoffer.dall@arm.com \
--cc=drjones@redhat.com \
--cc=james.morse@arm.com \
--cc=julien.thierry@arm.com \
--cc=kristina.martsenko@arm.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=marc.zyngier@arm.com \
--cc=mark.rutland@arm.com \
--cc=ramana.radhakrishnan@arm.com \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).