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[34.90.134.61]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5d652ae12a7sm4261850a12.50.2024.12.17.05.08.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Dec 2024 05:08:01 -0800 (PST) Date: Tue, 17 Dec 2024 13:07:58 +0000 From: Quentin Perret To: Marc Zyngier Cc: Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Fuad Tabba , Vincent Donnefort , Sebastian Ene , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 01/18] KVM: arm64: Change the layout of enum pkvm_page_state Message-ID: References: <20241216175803.2716565-1-qperret@google.com> <20241216175803.2716565-2-qperret@google.com> <861py6sht3.wl-maz@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <861py6sht3.wl-maz@kernel.org> On Tuesday 17 Dec 2024 at 10:52:08 (+0000), Marc Zyngier wrote: > On Mon, 16 Dec 2024 17:57:46 +0000, > Quentin Perret wrote: > > > > The 'concrete' (a.k.a non-meta) page states are currently encoded using > > software bits in PTEs. For performance reasons, the abstract > > pkvm_page_state enum uses the same bits to encode these states as that > > makes conversions from and to PTEs easy. > > > > In order to prepare the ground for moving the 'concrete' state storage > > to the hyp vmemmap, re-arrange the enum to use bits 0 and 1 for this > > purpose. > > > > No functional changes intended. > > > > Signed-off-by: Quentin Perret > > --- > > arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 16 +++++++++------- > > 1 file changed, 9 insertions(+), 7 deletions(-) > > > > diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h > > index 0972faccc2af..8c30362af2b9 100644 > > --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h > > +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h > > @@ -24,25 +24,27 @@ > > */ > > enum pkvm_page_state { > > PKVM_PAGE_OWNED = 0ULL, > > - PKVM_PAGE_SHARED_OWNED = KVM_PGTABLE_PROT_SW0, > > - PKVM_PAGE_SHARED_BORROWED = KVM_PGTABLE_PROT_SW1, > > - __PKVM_PAGE_RESERVED = KVM_PGTABLE_PROT_SW0 | > > - KVM_PGTABLE_PROT_SW1, > > + PKVM_PAGE_SHARED_OWNED = BIT(0), > > + PKVM_PAGE_SHARED_BORROWED = BIT(1), > > + __PKVM_PAGE_RESERVED = BIT(0) | BIT(1), > > > > /* Meta-states which aren't encoded directly in the PTE's SW bits */ > > - PKVM_NOPAGE, > > + PKVM_NOPAGE = BIT(2), > > }; > > +#define PKVM_PAGE_META_STATES_MASK (~(BIT(0) | BIT(1))) > > Shouldn't that be ~__PKVM_PAGE_RESERVED, given that you just defined it? Sure thing, I followed the same pattern as PKVM_PAGE_STATE_PROT_MASK which was explicit in which bits it sets, but very happy to change. > > > > #define PKVM_PAGE_STATE_PROT_MASK (KVM_PGTABLE_PROT_SW0 | KVM_PGTABLE_PROT_SW1) > > static inline enum kvm_pgtable_prot pkvm_mkstate(enum kvm_pgtable_prot prot, > > enum pkvm_page_state state) > > { > > - return (prot & ~PKVM_PAGE_STATE_PROT_MASK) | state; > > + prot &= ~PKVM_PAGE_STATE_PROT_MASK; > > + prot |= FIELD_PREP(PKVM_PAGE_STATE_PROT_MASK, state); > > + return prot; > > } > > > > static inline enum pkvm_page_state pkvm_getstate(enum kvm_pgtable_prot prot) > > { > > - return prot & PKVM_PAGE_STATE_PROT_MASK; > > + return FIELD_GET(PKVM_PAGE_STATE_PROT_MASK, prot); > > } > > > > struct host_mmu { > > Thanks, > > M. > > -- > Without deviation from the norm, progress is not possible.