From: Marc Zyngier <maz@kernel.org>
To: Oliver Upton <oupton@google.com>
Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel@lists.infradead.org,
Andrew Jones <drjones@redhat.com>,
Peter Shier <pshier@google.com>,
Ricardo Koller <ricarkol@google.com>,
Reiji Watanabe <reijiw@google.com>
Subject: Re: [PATCH v3 3/6] KVM: arm64: Allow guest to set the OSLK bit
Date: Mon, 29 Nov 2021 11:50:58 +0000 [thread overview]
Message-ID: <87sfvfmb8d.wl-maz@kernel.org> (raw)
In-Reply-To: <20211123210109.1605642-4-oupton@google.com>
On Tue, 23 Nov 2021 21:01:06 +0000,
Oliver Upton <oupton@google.com> wrote:
>
> Allow writes to OSLAR and forward the OSLK bit to OSLSR. Do nothing with
> the value for now.
>
> Reviewed-by: Reiji Watanabe <reijiw@google.com>
> Signed-off-by: Oliver Upton <oupton@google.com>
> ---
> arch/arm64/include/asm/sysreg.h | 6 ++++++
> arch/arm64/kvm/sys_regs.c | 33 ++++++++++++++++++++++++++-------
> 2 files changed, 32 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 16b3f1a1d468..9fad61a82047 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -129,7 +129,13 @@
> #define SYS_DBGWCRn_EL1(n) sys_reg(2, 0, 0, n, 7)
> #define SYS_MDRAR_EL1 sys_reg(2, 0, 1, 0, 0)
> #define SYS_OSLAR_EL1 sys_reg(2, 0, 1, 0, 4)
> +
> +#define SYS_OSLAR_OSLK BIT(0)
> +
> #define SYS_OSLSR_EL1 sys_reg(2, 0, 1, 1, 4)
> +
> +#define SYS_OSLSR_OSLK BIT(1)
> +
> #define SYS_OSDLR_EL1 sys_reg(2, 0, 1, 3, 4)
> #define SYS_DBGPRCR_EL1 sys_reg(2, 0, 1, 4, 4)
> #define SYS_DBGCLAIMSET_EL1 sys_reg(2, 0, 7, 8, 6)
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 7bf350b3d9cd..5dbdb45d6d44 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -44,6 +44,10 @@
> * 64bit interface.
> */
>
> +static int reg_from_user(u64 *val, const void __user *uaddr, u64 id);
> +static int reg_to_user(void __user *uaddr, const u64 *val, u64 id);
> +static u64 sys_reg_to_index(const struct sys_reg_desc *reg);
> +
> static bool read_from_write_only(struct kvm_vcpu *vcpu,
> struct sys_reg_params *params,
> const struct sys_reg_desc *r)
> @@ -287,6 +291,24 @@ static bool trap_loregion(struct kvm_vcpu *vcpu,
> return trap_raz_wi(vcpu, p, r);
> }
>
> +static bool trap_oslar_el1(struct kvm_vcpu *vcpu,
> + struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + u64 oslsr;
> +
> + if (!p->is_write)
> + return read_from_write_only(vcpu, p, r);
> +
> + /* Forward the OSLK bit to OSLSR */
> + oslsr = __vcpu_sys_reg(vcpu, OSLSR_EL1) & ~SYS_OSLSR_OSLK;
> + if (p->regval & SYS_OSLAR_OSLK)
> + oslsr |= SYS_OSLSR_OSLK;
> +
> + __vcpu_sys_reg(vcpu, OSLSR_EL1) = oslsr;
> + return true;
> +}
> +
> static bool trap_oslsr_el1(struct kvm_vcpu *vcpu,
> struct sys_reg_params *p,
> const struct sys_reg_desc *r)
> @@ -309,9 +331,10 @@ static int set_oslsr_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
> if (err)
> return err;
>
> - if (val != rd->val)
> + if ((val & ~SYS_OSLSR_OSLK) != rd->val)
> return -EINVAL;
This looks odd. It means that once I have set the lock from userspace,
I can't clear it?
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2021-11-29 11:52 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 21:01 [PATCH v3 0/6] KVM: arm64: Emulate the OS lock Oliver Upton
2021-11-23 21:01 ` [PATCH v3 1/6] KVM: arm64: Correctly treat writes to OSLSR_EL1 as undefined Oliver Upton
2021-11-23 21:01 ` [PATCH v3 2/6] KVM: arm64: Stash OSLSR_EL1 in the cpu context Oliver Upton
2021-11-23 21:01 ` [PATCH v3 3/6] KVM: arm64: Allow guest to set the OSLK bit Oliver Upton
2021-11-29 11:50 ` Marc Zyngier [this message]
2021-12-06 17:39 ` Oliver Upton
2021-12-06 18:47 ` Marc Zyngier
2021-11-23 21:01 ` [PATCH v3 4/6] KVM: arm64: Emulate the OS Lock Oliver Upton
2021-11-29 14:15 ` Marc Zyngier
2021-12-06 17:34 ` Oliver Upton
2021-11-23 21:01 ` [PATCH v3 5/6] selftests: KVM: Add OSLSR_EL1 to the list of blessed regs Oliver Upton
2021-11-23 21:01 ` [PATCH v3 6/6] selftests: KVM: Test OS lock behavior Oliver Upton
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