Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-20 Thread Marcel Apfelbaum
On 06/20/2016 01:42 PM, Igor Mammedov wrote: On Sun, 19 Jun 2016 19:13:17 +0300 Marcel Apfelbaum wrote: On 06/17/2016 07:07 PM, Laszlo Ersek wrote: On 06/17/16 11:52, Igor Mammedov wrote: On Fri, 17 Jun 2016 11:17:54 +0200 Gerd Hoffmann wrote: On Fr, 2016-06-17 at 10:43 +0200, Paolo Bonzi

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-20 Thread Igor Mammedov
On Sun, 19 Jun 2016 19:13:17 +0300 Marcel Apfelbaum wrote: > On 06/17/2016 07:07 PM, Laszlo Ersek wrote: > > On 06/17/16 11:52, Igor Mammedov wrote: > >> On Fri, 17 Jun 2016 11:17:54 +0200 > >> Gerd Hoffmann wrote: > >> > >>> On Fr, 2016-06-17 at 10:43 +0200, Paolo Bonzini wrote: > > O

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-20 Thread Paolo Bonzini
On 19/06/2016 05:36, Michael S. Tsirkin wrote: > > Making the guest's phys-bits larger than host-phys-bits would be okay if > > you reserve the area in the e820 and assume the guest doesn't touch it. > > How would it touch it if there's no RAM there? > PCI BARs is the only thing that comes to min

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-19 Thread Marcel Apfelbaum
On 06/17/2016 07:07 PM, Laszlo Ersek wrote: On 06/17/16 11:52, Igor Mammedov wrote: On Fri, 17 Jun 2016 11:17:54 +0200 Gerd Hoffmann wrote: On Fr, 2016-06-17 at 10:43 +0200, Paolo Bonzini wrote: On 17/06/2016 10:15, Dr. David Alan Gilbert wrote: Larger is a problem if the guest tries to ma

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-18 Thread Michael S. Tsirkin
On Fri, Jun 17, 2016 at 03:38:53PM +0200, Paolo Bonzini wrote: > Making the guest's phys-bits larger than host-phys-bits would be okay if > you reserve the area in the e820 and assume the guest doesn't touch it. How would it touch it if there's no RAM there? PCI BARs is the only thing that comes t

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Laszlo Ersek
On 06/17/16 13:20, Gerd Hoffmann wrote: > Hi, > >>> Not sure whenever qemu adds some extra space for hotplug to the 64bit >>> hole and if so how it calculates the size then. But the guest os should >>> stick to those ranges when configuring hotplugged devices. > >> currently firmware would ass

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Laszlo Ersek
On 06/17/16 11:52, Igor Mammedov wrote: > On Fri, 17 Jun 2016 11:17:54 +0200 > Gerd Hoffmann wrote: > >> On Fr, 2016-06-17 at 10:43 +0200, Paolo Bonzini wrote: >>> >>> On 17/06/2016 10:15, Dr. David Alan Gilbert wrote: Larger is a problem if the guest tries to map something to a high

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Eduardo Habkost
On Fri, Jun 17, 2016 at 05:28:03PM +0200, Paolo Bonzini wrote: > On 17/06/2016 17:19, Eduardo Habkost wrote: > > > > So, what happens if the guest play tricks in bits 40-45 when QEMU > > > > sets the limit to 40 but we are running in a 46-bit host? Is it > > > > really a problem? I assumed it would

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Eduardo Habkost
On Fri, Jun 17, 2016 at 03:38:53PM +0200, Paolo Bonzini wrote: > > > On 17/06/2016 15:18, Eduardo Habkost wrote: > > On Fri, Jun 17, 2016 at 09:15:06AM +0100, Dr. David Alan Gilbert wrote: > >> * Eduardo Habkost (ehabk...@redhat.com) wrote: > >>> On Thu, Jun 16, 2016 at 06:12:12PM +0100, Dr. Davi

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Paolo Bonzini
On 17/06/2016 17:19, Eduardo Habkost wrote: > > > So, what happens if the guest play tricks in bits 40-45 when QEMU > > > sets the limit to 40 but we are running in a 46-bit host? Is it > > > really a problem? I assumed it would be safe. > > > > The guest expects a "reserved bit set" page fault,

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Marcel Apfelbaum
On 06/17/2016 04:18 PM, Eduardo Habkost wrote: On Fri, Jun 17, 2016 at 09:15:06AM +0100, Dr. David Alan Gilbert wrote: * Eduardo Habkost (ehabk...@redhat.com) wrote: On Thu, Jun 16, 2016 at 06:12:12PM +0100, Dr. David Alan Gilbert (git) wrote: From: "Dr. David Alan Gilbert" Currently QEMU se

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Eduardo Habkost
On Fri, Jun 17, 2016 at 09:15:06AM +0100, Dr. David Alan Gilbert wrote: > * Eduardo Habkost (ehabk...@redhat.com) wrote: > > On Thu, Jun 16, 2016 at 06:12:12PM +0100, Dr. David Alan Gilbert (git) > > wrote: > > > From: "Dr. David Alan Gilbert" > > > > > > Currently QEMU sets the x86 number of ph

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Paolo Bonzini
On 17/06/2016 15:18, Eduardo Habkost wrote: > On Fri, Jun 17, 2016 at 09:15:06AM +0100, Dr. David Alan Gilbert wrote: >> * Eduardo Habkost (ehabk...@redhat.com) wrote: >>> On Thu, Jun 16, 2016 at 06:12:12PM +0100, Dr. David Alan Gilbert (git) >>> wrote: From: "Dr. David Alan Gilbert"

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Gerd Hoffmann
Hi, > > Not sure whenever qemu adds some extra space for hotplug to the 64bit > > hole and if so how it calculates the size then. But the guest os should > > stick to those ranges when configuring hotplugged devices. > currently firmware would assign 64-bit BARs after reserved-memory-end > (no

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Paolo Bonzini
On 17/06/2016 11:37, Dr. David Alan Gilbert wrote: >>> The existing 40-bit default looks like a problem for 36-bit >>> > > systems. Do you know what kind of systems have 36 bits only? Only >>> > > old ones, or recent ones too? If only old ones, how old? >> > >> > My Sandy Bridge (~2.5 year old)

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Igor Mammedov
On Fri, 17 Jun 2016 11:17:54 +0200 Gerd Hoffmann wrote: > On Fr, 2016-06-17 at 10:43 +0200, Paolo Bonzini wrote: > > > > On 17/06/2016 10:15, Dr. David Alan Gilbert wrote: > > > Larger is a problem if the guest tries to map something to a high > > > address that's not addressable. > > > > R

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Dr. David Alan Gilbert
* Dr. David Alan Gilbert (dgilb...@redhat.com) wrote: > * Eduardo Habkost (ehabk...@redhat.com) wrote: > > On Thu, Jun 16, 2016 at 06:12:12PM +0100, Dr. David Alan Gilbert (git) > > wrote: > > The existing 40-bit default looks like a problem for 36-bit > > systems. Do you know what kind of syst

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Gerd Hoffmann
On Fr, 2016-06-17 at 10:43 +0200, Paolo Bonzini wrote: > > On 17/06/2016 10:15, Dr. David Alan Gilbert wrote: > > Larger is a problem if the guest tries to map something to a high > > address that's not addressable. > > Right. It's not a problem for most emulated PCI devices (it would be a > pro

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Paolo Bonzini
On 17/06/2016 10:15, Dr. David Alan Gilbert wrote: > Larger is a problem if the guest tries to map something to a high > address that's not addressable. Right. It's not a problem for most emulated PCI devices (it would be a problem for those that have large RAM BARs, but even our emulated video

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-17 Thread Dr. David Alan Gilbert
* Eduardo Habkost (ehabk...@redhat.com) wrote: > On Thu, Jun 16, 2016 at 06:12:12PM +0100, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" > > > > Currently QEMU sets the x86 number of physical address bits to the > > magic number 40. This is only correct on some small AMD

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-16 Thread Eduardo Habkost
On Thu, Jun 16, 2016 at 06:12:12PM +0100, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" > > Currently QEMU sets the x86 number of physical address bits to the > magic number 40. This is only correct on some small AMD systems; > Intel systems tend to have 36, 39, 46 bits, a

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-16 Thread Eduardo Habkost
On Thu, Jun 16, 2016 at 07:26:01PM +0200, Paolo Bonzini wrote: > > > On 16/06/2016 19:12, Dr. David Alan Gilbert (git) wrote: > > if (env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_LM) { > > -/* 64 bit processor */ > > -/* XXX: The physical address space is limited to 42 bits

Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-16 Thread Paolo Bonzini
On 16/06/2016 19:12, Dr. David Alan Gilbert (git) wrote: > if (env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_LM) { > -/* 64 bit processor */ > -/* XXX: The physical address space is limited to 42 bits in exec.c. */ > -*eax = 0x3028; /* 48 bits virtual, 40 bit

[Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

2016-06-16 Thread Dr. David Alan Gilbert (git)
From: "Dr. David Alan Gilbert" Currently QEMU sets the x86 number of physical address bits to the magic number 40. This is only correct on some small AMD systems; Intel systems tend to have 36, 39, 46 bits, and large AMD systems tend to have 48. Having the value different from your actual hardw