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charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: Russell King (Oracle) On Fri, Apr 18, 2025 at 11:14:48AM -0400, Yury Norov wrote: > On Thu, Apr 17, 2025 at 12:23:10PM +0100, Marc Zyngier wrote: > > On Thu, 17 Apr 2025 11:47:11 +0100, > > Luo Jie wrote: > > > > > > Replaced below code with the wrapper FIELD_MODIFY(MASK, ®, val) > > > - reg &= ~MASK; > > > - reg |= FIELD_PREP(MASK, val); > > > The semantic patch that makes this change is available > > > in scripts/coccinelle/misc/field_modify.cocci. > > > > > > More information about semantic patching is available at > > > https://coccinelle.gitlabpages.inria.fr/website > > > > > > Signed-off-by: Luo Jie > > > --- > > > arch/arm64/kvm/hyp/include/nvhe/memory.h | 3 +-- > > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > > > diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h > > > index 34233d586060..b2af748964d0 100644 > > > --- a/arch/arm64/kvm/hyp/include/nvhe/memory.h > > > +++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h > > > @@ -30,8 +30,7 @@ enum pkvm_page_state { > > > static inline enum kvm_pgtable_prot pkvm_mkstate(enum kvm_pgtable_prot prot, > > > enum pkvm_page_state state) > > > { > > > - prot &= ~PKVM_PAGE_STATE_PROT_MASK; > > > - prot |= FIELD_PREP(PKVM_PAGE_STATE_PROT_MASK, state); > > > + FIELD_MODIFY(PKVM_PAGE_STATE_PROT_MASK, &prot, state); > > > return prot; > > > } > > > > Following up on my suggestion to *not* add anything new, this patch > > could be written as: > > > > diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h > > index 34233d5860607..08cb6ba0e0716 100644 > > --- a/arch/arm64/kvm/hyp/include/nvhe/memory.h > > +++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h > > @@ -30,9 +30,8 @@ enum pkvm_page_state { > > static inline enum kvm_pgtable_prot pkvm_mkstate(enum kvm_pgtable_prot prot, > > enum pkvm_page_state state) > > { > > - prot &= ~PKVM_PAGE_STATE_PROT_MASK; > > - prot |= FIELD_PREP(PKVM_PAGE_STATE_PROT_MASK, state); > > - return prot; > > + u64 p = prot; > > + return u64_replace_bits(p, state, PKVM_PAGE_STATE_PROT_MASK); > > } > > This is a great example where u64_replace_bit() should NOT be used. Why not? Explain it. Don't leave people in the dark, because right now it looks like it's purely a religous fanaticism about what should and should not be used. Where's the technical reasoning? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!