| Message ID | 61084180-d44a-4664-be13-462706587668@suse.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | IOMMU: iommu_use_hap_pt() implies CONFIG_HVM | expand |
On 31/01/2024 9:20 am, Jan Beulich wrote: > Allow the compiler a little more room on DCE by moving the compile-time- > constant condition into the predicate (from the one place where it was > added in an open-coded fashion for XSA-450). > > Signed-off-by: Jan Beulich <jbeulich@suse.com> Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> I'm surprised that's happy compiling if it's actually doing anything at all, given that it's an unguarded variable reference.
On 31.01.2024 11:40, Andrew Cooper wrote: > On 31/01/2024 9:20 am, Jan Beulich wrote: >> Allow the compiler a little more room on DCE by moving the compile-time- >> constant condition into the predicate (from the one place where it was >> added in an open-coded fashion for XSA-450). >> >> Signed-off-by: Jan Beulich <jbeulich@suse.com> > > Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> Thanks, but ... > I'm surprised that's happy compiling if it's actually doing anything at > all, given that it's an unguarded variable reference. ... I'm afraid I don't understand: What "unguarded variable reference" are you seeing me add? Even if you were talking about the hap_pt_share struct field (which was accessed before as well) - that's part of struct domain_iommu no matter what .config has. Jan
On 31/01/2024 11:09 am, Jan Beulich wrote: > On 31.01.2024 11:40, Andrew Cooper wrote: >> On 31/01/2024 9:20 am, Jan Beulich wrote: >>> Allow the compiler a little more room on DCE by moving the compile-time- >>> constant condition into the predicate (from the one place where it was >>> added in an open-coded fashion for XSA-450). >>> >>> Signed-off-by: Jan Beulich <jbeulich@suse.com> >> Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> > Thanks, but ... > >> I'm surprised that's happy compiling if it's actually doing anything at >> all, given that it's an unguarded variable reference. > ... I'm afraid I don't understand: What "unguarded variable reference" > are you seeing me add? Even if you were talking about the hap_pt_share > struct field (which was accessed before as well) - that's part of > struct domain_iommu no matter what .config has. Ah. That will be why it compiles. Fine. ~Andrew
--- a/xen/drivers/passthrough/vtd/iommu.c +++ b/xen/drivers/passthrough/vtd/iommu.c @@ -438,7 +438,7 @@ static paddr_t domain_pgd_maddr(struct d if ( pgd_maddr ) /* nothing */; - else if ( IS_ENABLED(CONFIG_HVM) && iommu_use_hap_pt(d) ) + else if ( iommu_use_hap_pt(d) ) { pagetable_t pgt = p2m_get_pagetable(p2m_get_hostp2m(d)); --- a/xen/include/xen/iommu.h +++ b/xen/include/xen/iommu.h @@ -381,7 +381,8 @@ struct domain_iommu { #define iommu_clear_feature(d, f) clear_bit(f, dom_iommu(d)->features) /* Are we using the domain P2M table as its IOMMU pagetable? */ -#define iommu_use_hap_pt(d) (dom_iommu(d)->hap_pt_share) +#define iommu_use_hap_pt(d) (IS_ENABLED(CONFIG_HVM) && \ + dom_iommu(d)->hap_pt_share) /* Does the IOMMU pagetable need to be kept synchronized with the P2M */ #ifdef CONFIG_HAS_PASSTHROUGH
Allow the compiler a little more room on DCE by moving the compile-time- constant condition into the predicate (from the one place where it was added in an open-coded fashion for XSA-450). Signed-off-by: Jan Beulich <jbeulich@suse.com>