From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Elias El Yandouzi <eliasely@amazon.com>
Cc: xen-devel@lists.xenproject.org, julien@xen.org,
pdurrant@amazon.com, dwmw@amazon.com,
Julien Grall <jgrall@amazon.com>
Subject: Re: [PATCH V3 01/19] x86: Create per-domain mapping of guest_root_pt
Date: Wed, 15 May 2024 11:05:15 +0200 [thread overview]
Message-ID: <ZkR6y3kuvKySKwRm@macbook> (raw)
In-Reply-To: <699c6487-58c9-456f-8415-e3c525fa905e@amazon.com>
On Tue, May 14, 2024 at 06:15:57PM +0100, Elias El Yandouzi wrote:
> Hi Roger,
>
> On 13/05/2024 16:27, Roger Pau Monné wrote:
> > > diff --git a/xen/arch/x86/pv/domain.c b/xen/arch/x86/pv/domain.c
> > > index 2a445bb17b..1b025986f7 100644
> > > --- a/xen/arch/x86/pv/domain.c
> > > +++ b/xen/arch/x86/pv/domain.c
> > > @@ -288,6 +288,21 @@ static void pv_destroy_gdt_ldt_l1tab(struct vcpu *v)
> > > 1U << GDT_LDT_VCPU_SHIFT);
> > > }
> > > +static int pv_create_root_pt_l1tab(struct vcpu *v)
> > > +{
> > > + return create_perdomain_mapping(v->domain,
> > > + PV_ROOT_PT_MAPPING_VCPU_VIRT_START(v),
> > > + 1, v->domain->arch.pv.root_pt_l1tab,
> > > + NULL);
> > > +}
> > > +
> > > +static void pv_destroy_root_pt_l1tab(struct vcpu *v)
> >
> > The two 'v' parameters could be const here.
>
> I could constify the parameters but the functions wouldn't be consistent
> with the two above for gdt/ldt.
The fact they are not const for the other helpers would also need
fixing at some point IMO, it's best if those are already using the
correct type.
> > > diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
> > > index df015589ce..c1377da7a5 100644
> > > --- a/xen/arch/x86/x86_64/entry.S
> > > +++ b/xen/arch/x86/x86_64/entry.S
> > > @@ -162,7 +162,15 @@ FUNC_LOCAL(restore_all_guest)
> > > and %rsi, %rdi
> > > and %r9, %rsi
> > > add %rcx, %rdi
> > > +
> > > + /*
> > > + * The address in the vCPU cr3 is always mapped in the per-domain
> > > + * pv_root_pt virt area.
> > > + */
> > > + imul $PAGE_SIZE, VCPU_id(%rbx), %esi
> >
> > Aren't some of the previous operations against %rsi now useless since
> > it gets unconditionally overwritten here?
>
> I think I can just get rid off of:
>
> and %r9, %rsi
>
> > and %r9, %rsi
> > [...]
> > add %rcx, %rsi
>
> The second operation you suggested is actually used to retrieve the VA of
> the PV_ROOT_PT.
Oh, yes, sorry, got confused when looking at the source file together
with the diff, it's only the `and` that can be removed.
Thanks, Roger.
next prev parent reply other threads:[~2024-05-15 9:05 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-13 11:10 [PATCH V3 00/19] Remove the directmap Elias El Yandouzi
2024-05-13 11:10 ` [PATCH V3 01/19] x86: Create per-domain mapping of guest_root_pt Elias El Yandouzi
2024-05-13 15:27 ` Roger Pau Monné
2024-05-14 8:03 ` Jan Beulich
2024-05-14 15:46 ` Alejandro Vallejo
2024-05-14 17:15 ` Elias El Yandouzi
2024-05-15 9:05 ` Roger Pau Monné [this message]
2024-05-13 11:11 ` [PATCH V3 02/19] x86/pv: Domheap pages should be mapped while relocating initrd Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 03/19] x86/pv: Rewrite how building PV dom0 handles domheap mappings Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 04/19] x86: Lift mapcache variable to the arch level Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 05/19] x86/mapcache: Initialise the mapcache for the idle domain Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 06/19] x86: Add a boot option to enable and disable the direct map Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 07/19] xen/x86: Add support for the PMAP Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 08/19] xen/x86: Add build assertion for fixmap entries Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 09/19] x86/domain_page: Remove the fast paths when mfn is not in the directmap Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 10/19] xen/page_alloc: Add a path for xenheap when there is no direct map Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 11/19] x86/setup: Leave early boot slightly earlier Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 12/19] x86/setup: vmap heap nodes when they are outside the direct map Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 13/19] x86/setup: Do not create valid mappings when directmap=no Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 14/19] Rename mfn_to_virt() calls Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 15/19] Rename maddr_to_virt() calls Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 16/19] xen/arm32: mm: Rename 'first' to 'root' in init_secondary_pagetables() Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 17/19] xen/arm64: mm: Use per-pCPU page-tables Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 18/19] xen/arm64: Implement a mapcache for arm64 Elias El Yandouzi
2024-05-13 11:11 ` [PATCH V3 19/19] xen/arm64: Allow the admin to enable/disable the directmap Elias El Yandouzi
2024-05-13 12:52 ` [PATCH V3 00/19] Remove " Roger Pau Monné
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