From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Steven Price <steven.price@arm.com>
Cc: "Marc Zyngier" <maz@kernel.org>, "Will Deacon" <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Russell King" <linux@armlinux.org.uk>,
"James Morse" <james.morse@arm.com>,
"Julien Thierry" <julien.thierry.kdev@gmail.com>,
"Suzuki K Pouloze" <suzuki.poulose@arm.com>,
"Mark Rutland" <mark.rutland@arm.com>,
kvm@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 04/10] KVM: Implement kvm_put_guest()
Date: Thu, 22 Aug 2019 08:28:54 -0700 [thread overview]
Message-ID: <20190822152854.GE25467@linux.intel.com> (raw)
In-Reply-To: <20190821153656.33429-5-steven.price@arm.com>
On Wed, Aug 21, 2019 at 04:36:50PM +0100, Steven Price wrote:
> kvm_put_guest() is analogous to put_user() - it writes a single value to
> the guest physical address. The implementation is built upon put_user()
> and so it has the same single copy atomic properties.
What you mean by "single copy atomic"? I.e. what guarantees does
put_user() provide that __copy_to_user() does not?
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> include/linux/kvm_host.h | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index fcb46b3374c6..e154a1897e20 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -746,6 +746,30 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> unsigned long len);
> int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> gpa_t gpa, unsigned long len);
> +
> +#define __kvm_put_guest(kvm, gfn, offset, value, type) \
> +({ \
> + unsigned long __addr = gfn_to_hva(kvm, gfn); \
> + type __user *__uaddr = (type __user *)(__addr + offset); \
> + int __ret = 0; \
> + \
> + if (kvm_is_error_hva(__addr)) \
> + __ret = -EFAULT; \
> + else \
> + __ret = put_user(value, __uaddr); \
> + if (!__ret) \
> + mark_page_dirty(kvm, gfn); \
> + __ret; \
> +})
> +
> +#define kvm_put_guest(kvm, gpa, value, type) \
> +({ \
> + gpa_t __gpa = gpa; \
> + struct kvm *__kvm = kvm; \
> + __kvm_put_guest(__kvm, __gpa >> PAGE_SHIFT, \
> + offset_in_page(__gpa), (value), type); \
> +})
> +
> int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
> int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
> struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
> --
> 2.20.1
>
next prev parent reply other threads:[~2019-08-22 15:28 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 15:36 [PATCH v3 00/10] arm64: Stolen time support Steven Price
2019-08-21 15:36 ` [PATCH v3 01/10] KVM: arm64: Document PV-time interface Steven Price
2019-08-27 8:44 ` Christoffer Dall
2019-08-28 11:23 ` Steven Price
2019-08-27 8:57 ` Christoffer Dall
2019-08-28 12:09 ` Steven Price
2019-08-30 9:22 ` Christoffer Dall
2019-08-28 13:49 ` Christoffer Dall
2019-08-29 15:21 ` Steven Price
2019-08-29 17:15 ` Andrew Jones
2019-08-30 8:35 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 02/10] KVM: arm/arm64: Factor out hypercall handling from PSCI code Steven Price
2019-08-21 15:36 ` [PATCH v3 03/10] KVM: arm64: Implement PV_FEATURES call Steven Price
2019-08-21 15:36 ` [PATCH v3 04/10] KVM: Implement kvm_put_guest() Steven Price
2019-08-22 10:29 ` Jonathan Cameron
2019-08-22 10:37 ` Steven Price
2019-08-22 15:28 ` Sean Christopherson [this message]
2019-08-22 15:46 ` Steven Price
2019-08-22 16:24 ` Sean Christopherson
2019-08-23 10:33 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 05/10] KVM: arm64: Support stolen time reporting via shared structure Steven Price
2019-08-22 10:39 ` Jonathan Cameron
2019-08-22 11:00 ` Steven Price
2019-08-23 12:07 ` Zenghui Yu
2019-08-23 13:23 ` Steven Price
2019-08-21 15:36 ` [PATCH v3 06/10] KVM: Allow kvm_device_ops to be const Steven Price
2019-08-21 15:36 ` [PATCH v3 07/10] KVM: arm64: Provide a PV_TIME device to user space Steven Price
2019-08-22 10:57 ` Jonathan Cameron
2019-08-22 11:11 ` Steven Price
2019-08-22 11:48 ` Jonathan Cameron
2019-08-21 15:36 ` [PATCH v3 08/10] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Steven Price
2019-08-21 15:36 ` [PATCH v3 09/10] arm/arm64: Make use of the SMCCC 1.1 wrapper Steven Price
2019-08-21 15:36 ` [PATCH v3 10/10] arm64: Retrieve stolen time as paravirtualized guest Steven Price
2019-08-23 11:45 ` Zenghui Yu
2019-08-23 14:22 ` Steven Price
2019-08-27 12:43 ` Zenghui Yu
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