From: "Raslan, KarimAllah" <karahmed@amazon.de>
To: "pbonzini@redhat.com" <pbonzini@redhat.com>,
"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"rkrcmar@redhat.com" <rkrcmar@redhat.com>
Subject: Re: [PATCH v5 00/13] KVM/X86: Introduce a new guest mapping interface
Date: Thu, 31 Jan 2019 13:03:26 +0000 [thread overview]
Message-ID: <1548939805.28936.9.camel@amazon.de> (raw)
In-Reply-To: <72d9954b-37f8-3f39-37f7-b292766da480@redhat.com>
On Wed, 2019-01-30 at 18:14 +0100, Paolo Bonzini wrote:
> On 25/01/19 19:28, Raslan, KarimAllah wrote:
> >
> > So the simple way to do it is:
> >
> > 1- Pass 'mem=' in the kernel command-line to limit the amount of memory managed
> > by the kernel.
> > 2- Map this physical memory you want to give to the guest with
> > mmap("/dev/mem", physical_address_offset, ..)
> > 3- Use the user-space virtual address as the "userspace_addr" field
> > in KVM_SET_USER_MEMORY_REGION ioctl.
> >
> > You will also need this patch (hopefully I will repost next week as well):
> > https://patchwork.kernel.org/patch/9191755/
>
> I took a look again at that patch and I guess I've changed my mind now
> that the kernel provides e820__mapped_any and e820__mapped_all.
> However, please do use e820__mapped_any instead of adding a new function
> e820_is_ram.
The problem with e820__mapped_* is that they are iterating over 'e820_table'
which is already truncated from the 'mem=' and 'memmap=' parameters:
"""
* - 'e820_table': this is the main E820 table that is massaged by the
* low level x86 platform code, or modified by boot parameters, before
* passed on to higher level MM layers.
"""
.. so I really still can not use it for this purpose. The structure that I want
to look at is actually 'e820_table_firmware' which is:
"""
* - 'e820_table_firmware': the original firmware version passed to us by the
* bootloader - not modified by the kernel. It is composed of two parts:
* the first 128 E820 memory entries in boot_params.e820_table and the
remaining
* (if any) entries of the SETUP_E820_EXT nodes. We use this to:
*
* - inform the user about the firmware's notion of memory layout
* via /sys/firmware/memmap
*
* - the hibernation code uses it to generate a kernel-independent MD5
* fingerprint of the physical memory layout of a system.
"""
The users of e820__mapped_any expect these semantics, so even changing the
implementation of these functions to use 'e820_table_firmware' to handle this
will not be an option!
One option here would be to add 'e820__mapped_raw_any' (or whatever
other name) and make it identical to the current implementation of
e820__mapped_any at. Would that be slightly more acceptable? :)
>
> Thanks,
>
> Paolo
>
> >
> > I will make sure to expand on this in the cover letter in v6.
>
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Krausenstr. 38
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next prev parent reply other threads:[~2019-01-31 13:03 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-09 9:42 [PATCH v5 00/13] KVM/X86: Introduce a new guest mapping interface KarimAllah Ahmed
2019-01-09 9:42 ` [PATCH v5 01/13] X86/nVMX: handle_vmon: Read 4 bytes from guest memory KarimAllah Ahmed
2019-01-23 16:59 ` Konrad Rzeszutek Wilk
2019-01-09 9:42 ` [PATCH v5 02/13] X86/nVMX: Update the PML table without mapping and unmapping the page KarimAllah Ahmed
2019-01-23 17:17 ` Konrad Rzeszutek Wilk
2019-01-09 9:42 ` [PATCH v5 03/13] X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs KarimAllah Ahmed
2019-01-23 17:31 ` Konrad Rzeszutek Wilk
2019-01-09 9:42 ` [PATCH v5 04/13] KVM: Introduce a new guest mapping API KarimAllah Ahmed
2019-01-10 13:07 ` David Hildenbrand
2019-01-25 18:01 ` Raslan, KarimAllah
2019-01-23 17:41 ` Konrad Rzeszutek Wilk
2019-01-23 17:50 ` Konrad Rzeszutek Wilk
2019-01-25 18:09 ` Raslan, KarimAllah
2019-01-30 17:08 ` Paolo Bonzini
2019-01-09 9:42 ` [PATCH v5 05/13] X86/nVMX: handle_vmptrld: Use kvm_vcpu_map when copying VMCS12 from guest memory KarimAllah Ahmed
2019-01-23 17:44 ` Konrad Rzeszutek Wilk
2019-01-09 9:42 ` [PATCH v5 06/13] KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap KarimAllah Ahmed
2019-01-09 9:42 ` [PATCH v5 07/13] KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page KarimAllah Ahmed
2019-01-23 17:57 ` Konrad Rzeszutek Wilk
2019-01-25 18:14 ` Raslan, KarimAllah
2019-01-09 9:42 ` [PATCH v5 08/13] KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt descriptor table KarimAllah Ahmed
2019-01-23 18:03 ` Konrad Rzeszutek Wilk
2019-01-25 18:15 ` Raslan, KarimAllah
2019-01-09 9:42 ` [PATCH v5 09/13] KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated KarimAllah Ahmed
2019-01-23 18:04 ` Konrad Rzeszutek Wilk
2019-01-09 9:42 ` [PATCH v5 10/13] KVM/nSVM: Use the new mapping API for mapping guest memory KarimAllah Ahmed
2019-01-23 18:08 ` Konrad Rzeszutek Wilk
2019-01-09 9:42 ` [PATCH v5 11/13] KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS KarimAllah Ahmed
2019-01-23 18:10 ` Konrad Rzeszutek Wilk
2019-01-09 9:42 ` [PATCH v5 12/13] KVM/nVMX: Use kvm_vcpu_map for accessing the enlightened VMCS KarimAllah Ahmed
2019-01-23 18:11 ` Konrad Rzeszutek Wilk
2019-01-09 9:42 ` [PATCH v5 13/13] KVM/nVMX: Use page_address_valid in a few more locations KarimAllah Ahmed
2019-01-23 18:18 ` Konrad Rzeszutek Wilk
2019-01-25 18:17 ` Raslan, KarimAllah
2019-01-23 18:16 ` [PATCH v5 00/13] KVM/X86: Introduce a new guest mapping interface Konrad Rzeszutek Wilk
2019-01-25 18:28 ` Raslan, KarimAllah
2019-01-30 17:14 ` Paolo Bonzini
2019-01-31 13:03 ` Raslan, KarimAllah [this message]
2019-01-31 13:10 ` Paolo Bonzini
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