On Tue, 2022-12-06 at 12:07 +0100, Philippe Mathieu-Daudé wrote: > On 6/12/22 10:40, David Woodhouse wrote: > > On Tue, 2022-12-06 at 09:16 +0100, Philippe Mathieu-Daudé wrote: > > > +Thomas > > > > > > On 6/12/22 02:10, David Woodhouse wrote: > > > > On Mon, 2022-12-05 at 23:11 +0100, Philippe Mathieu-Daudé > > > > wrote: > > > > > On 5/12/22 18:31, David Woodhouse wrote: > > > > > > +#ifdef CONFIG_XEN > > > > > > > > > > CONFIG_XEN is set when the _host_ has Xen development files > > > > > available. > > > > > > > > > > IIUC here you want to check if Xen HVM guest support is > > > > > enabled. > > > > > > > > > > You might want to use a different CONFIG_XEN_xxx key, which > > > > > itself > > > > > depends on CONFIG_XEN. > > > > > > > > Yeah, I'd be interested in opinions on that one. > > > > > > > > Strictly, the only one that *needs* to be a configure option is > > > > CONFIG_XEN for the Xen libraries, which is support for actually > > > > running > > > > on Xen. > > > > > > > > Any time KVM is present, we *could* pull in the rest of the > > > > xenfv > > > > machine support unconditionally, since that's no longer > > > > dependent on > > > > true Xen. > > > > > > > > But because there's a non-trivial amount of code in the event > > > > channel > > > > and grant table stuff, *perhaps* we want to make it optional? I > > > > don't > > > > really want to call that CONFIG_KVM_XEN since as noted, it's > > > > theoretically possible to do it with TCG or other accelerators > > > > too. So > > > > we could call it CONFIG_XEN_EMULATION. > > > > > > I concur CONFIG_KVM_XEN is confusing; CONFIG_XEN_EMULATION / > > > CONFIG_XEN_EMU sounds better. > > > > > > Is it useful to have the CONFIG_XEN_EMU code under target/i386/ > > > built > > > without having the xenfv machine built in? > > > > It isn't useful, no. > > > > > I rather have hw/ and target/ features disentangled, so I'd use > > > CONFIG_XEN_EMU under target/ and CONFIG_XENFV_MACHINE under hw/, > > > eventually having CONFIG_XEN_EMU depending on > > > CONFIG_XENFV_MACHINE > > > and -- for now -- CONFIG_KVM. > > > > Hm, I was thinking of XENFV_MACHINE as the parts which are needed > > by > > *both* XEN_EMU and real Xen. I think there are arch-independent > > things > > which want to go into hw/ like event channels and grant table > > support; > > you can think of those as an IRQ chip and an IOMMU respectively. > > Since > > those are emulation-only, they want to be conditional on XEN_EMU, > > not > > XENFV_MACHINE. > > > > The core hypercall support lives in target/ and would call directly > > to > > gnttab_op/evtchn_op functions in hw/xen/ but I think that's OK. The > > vCPU-specific things like timers and runstate can also stay in > > target/. > > > > Nothing in hw/ should explicitly mention KVM; the code in > > target/i386/xen.c should wrap the KVM-specific implementations > > unless > > the pretence of future TCG support is really making it look awful. > > > > Does that sound reasonable? Probably close enough, and we can take > > an > > other look at it once we see how it works out. > > > > > > I don't think we'd make that depend on CONFIG_XEN though, since > > > > none of > > > > the actual Xen libraries would be needed once everything's > > > > implemented > > > > and cleaned up. > > > > > > Agreed. > > > > > > > So things like the xenfv machine code would then depend on > > > > (CONFIG_XEN || CONFIG_XEN_EMULATION)... or we could make a new > > > > automatic config symbol CONFIG_XEN_MACHINE which has the same > > > > effect? > > > > > > So per what you just cleared, not CONFIG_XEN but CONFIG_KVM. > > > > I think it looks something like this... > > > > From 0a90999e37ec48b7fbd0467c243769b9bf726401 Mon Sep 17 00:00:00 > > 2001 > > From: David Woodhouse < > > d...@amazon.co.uk > > > > > Date: Tue, 6 Dec 2022 09:03:48 +0000 > > Subject: [PATCH] Add CONFIG_XENFV_MACHINE and CONFIG_XEN_EMU > > options for Xen > > emulation > > > > The XEN_EMU option will cover core Xen support in target/, which > > exists > > only for x86 with KVM today but could theoretically also be > > implemented > > on Arm/Aarch64 and with TCG or other accelerators. It will also > > cover > > the support for architecture-independent grant table and event > > channel > > support which will be added in hw/xen/. > > > > The XENFV_MACHINE option is for the xenfv platform support, which > > will > > now be used both by XEN_EMU and by real Xen. > > > > The XEN option remains dependent on the Xen runtime libraries, and > > covers > > support for real Xen. Some code which currently resides under > > CONFIG_XEN > > will be moving to CONFIG_XENFV_MACHINE over time. > > > > Signed-off-by: David Woodhouse <d...@amazon.co.uk> > > --- > > accel/Kconfig | 2 ++ > > hw/Kconfig | 1 + > > hw/xen/Kconfig | 2 ++ > > meson.build | 1 + > > target/Kconfig | 3 +++ > > 5 files changed, 9 insertions(+) > > create mode 100644 hw/xen/Kconfig > > > > diff --git a/accel/Kconfig b/accel/Kconfig > > index 8bdedb7d15..87d2880cad 100644 > > --- a/accel/Kconfig > > +++ b/accel/Kconfig > > @@ -15,7 +15,9 @@ config TCG > > > > config KVM > > bool > > + select XEN_EMU if (I386 || X86_64) > > We certainly can build KVM without XEN_EMU... > > You might want to s/select/imply/ here.
OK.
> > config XEN
> > bool
> > select FSDEV_9P if VIRTFS
> > + select XENFV_MACHINE
>
> This is the XEN (host) accelerator switch... You said previously
> it is not related to the guest xenfv machine.
The xenfv platform definition, and various other things like the Xen
PCI platform device, are currently covered by CONFIG_XEN.
The idea is that we'd change that to CONFIG_XENFV_MACHINE so that they
can be present if *either* CONFIG_XEN or CONFIG_XEN_EMU are enabled.
So (given your later comment about target features not selecting a a
hw/machine component) I've made it:
config XENFV_MACHINE
bool
default y if (XEN || XEN_EMU)
How's this...
From eaff99027a888aac8a5df554ef22f37dc271be66 Mon Sep 17 00:00:00 2001
From: David Woodhouse <d...@amazon.co.uk>
Date: Tue, 6 Dec 2022 09:03:48 +0000
Subject: [PATCH] Add CONFIG_XENFV_MACHINE and CONFIG_XEN_EMU options for Xen
emulation
The XEN_EMU option will cover core Xen support in target/, which exists
only for x86 with KVM today but could theoretically also be implemented
on Arm/Aarch64 and with TCG or other accelerators. It will also cover
the support for architecture-independent grant table and event channel
support which will be added in hw/xen/.
The XENFV_MACHINE option is for the xenfv platform support, which will
now be used both by XEN_EMU and by real Xen.
The XEN option remains dependent on the Xen runtime libraries, and covers
support for real Xen. Some code which currently resides under CONFIG_XEN
will be moving to CONFIG_XENFV_MACHINE over time.
Signed-off-by: David Woodhouse <d...@amazon.co.uk>
---
accel/Kconfig | 1 +
hw/Kconfig | 1 +
hw/xen/Kconfig | 3 +++
meson.build | 1 +
target/Kconfig | 4 ++++
5 files changed, 10 insertions(+)
create mode 100644 hw/xen/Kconfig
diff --git a/accel/Kconfig b/accel/Kconfig
index 8bdedb7d15..41e089e610 100644
--- a/accel/Kconfig
+++ b/accel/Kconfig
@@ -15,6 +15,7 @@ config TCG
config KVM
bool
+ imply XEN_EMU if (I386 || X86_64)
config XEN
bool
diff --git a/hw/Kconfig b/hw/Kconfig
index 38233bbb0f..ba62ff6417 100644
--- a/hw/Kconfig
+++ b/hw/Kconfig
@@ -41,6 +41,7 @@ source tpm/Kconfig
source usb/Kconfig
source virtio/Kconfig
source vfio/Kconfig
+source xen/Kconfig
source watchdog/Kconfig
# arch Kconfig
diff --git a/hw/xen/Kconfig b/hw/xen/Kconfig
new file mode 100644
index 0000000000..755c8b1faf
--- /dev/null
+++ b/hw/xen/Kconfig
@@ -0,0 +1,3 @@
+config XENFV_MACHINE
+ bool
+ default y if (XEN || XEN_EMU)
diff --git a/meson.build b/meson.build
index 5c6b5a1c75..9348cf572c 100644
--- a/meson.build
+++ b/meson.build
@@ -3828,6 +3828,7 @@ if have_system
if xen.found()
summary_info += {'xen ctrl version': xen.version()}
endif
+ summary_info += {'Xen emulation': config_all.has_key('CONFIG_XEN_EMU')}
endif
summary_info += {'TCG support': config_all.has_key('CONFIG_TCG')}
if config_all.has_key('CONFIG_TCG')
diff --git a/target/Kconfig b/target/Kconfig
index 83da0bd293..e19c9d77b5 100644
--- a/target/Kconfig
+++ b/target/Kconfig
@@ -18,3 +18,7 @@ source sh4/Kconfig
source sparc/Kconfig
source tricore/Kconfig
source xtensa/Kconfig
+
+config XEN_EMU
+ bool
+ depends on KVM && (I386 || X86_64)
--
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