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Wed, 21 Apr 2021 01:33:05 -0400 (EDT) Received: by mail.kernel.org (Postfix) with ESMTPSA id 2202B6141E; Wed, 21 Apr 2021 05:32:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618983184; bh=s6EiU6upxSMVY7x8MjwXYvtafRVu/QAM7lsLlrk8yoE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BgxWarU4gpoVTkgPVuxb2PqYka+WSztPMpSDxztTHqTCCeNyCtFju/nT+RSyzfrMN xq/+7X37yPwUBFVumuSRWKEPwL+Acd7hwN29dD0XqHteWavlHR89NcENNzGl5h+AEx 7zoZXaEFsCm58Y+GZHTVLHasIcZtyuVLjlwGXDDiMyULjQ1+IMNvrYQksOOB3n6zuG CprtRV+XLF8mgBRDBFCDrgyEy0C4GPjkvT7q1t8/LkJZGiCc3FicAmm7/dPeh0Xzud ON5IqHD7qdXOY/6ZzKs8r1BS/pHC5Zcr5mGi4d6vGJm9gd/3eAb8ggcURZPMUShL3W k0jf1kymQjU8Q== Date: Wed, 21 Apr 2021 08:32:55 +0300 From: Mike Rapoport To: David Hildenbrand Subject: Re: [PATCH v1 3/4] arm64: decouple check whether pfn is in linear map from pfn_valid() Message-ID: References: <20210420090925.7457-1-rppt@kernel.org> <20210420090925.7457-4-rppt@kernel.org> <29b51a80-1543-fcec-6f5b-5ae21b78e1e9@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <29b51a80-1543-fcec-6f5b-5ae21b78e1e9@redhat.com> Cc: Anshuman Khandual , Catalin Marinas , linux-kernel@vger.kernel.org, Mike Rapoport , linux-mm@kvack.org, kvmarm@lists.cs.columbia.edu, Marc Zyngier , Will Deacon , linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Tue, Apr 20, 2021 at 05:57:57PM +0200, David Hildenbrand wrote: > On 20.04.21 11:09, Mike Rapoport wrote: > > From: Mike Rapoport > > > > The intended semantics of pfn_valid() is to verify whether there is a > > struct page for the pfn in question and nothing else. > > > > Yet, on arm64 it is used to distinguish memory areas that are mapped in the > > linear map vs those that require ioremap() to access them. > > > > Introduce a dedicated pfn_is_map_memory() wrapper for > > memblock_is_map_memory() to perform such check and use it where > > appropriate. > > > > Using a wrapper allows to avoid cyclic include dependencies. > > > > Signed-off-by: Mike Rapoport > > --- > > arch/arm64/include/asm/memory.h | 2 +- > > arch/arm64/include/asm/page.h | 1 + > > arch/arm64/kvm/mmu.c | 2 +- > > arch/arm64/mm/init.c | 6 ++++++ > > arch/arm64/mm/ioremap.c | 4 ++-- > > arch/arm64/mm/mmu.c | 2 +- > > 6 files changed, 12 insertions(+), 5 deletions(-) > > > > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h > > index 0aabc3be9a75..194f9f993d30 100644 > > --- a/arch/arm64/include/asm/memory.h > > +++ b/arch/arm64/include/asm/memory.h > > @@ -351,7 +351,7 @@ static inline void *phys_to_virt(phys_addr_t x) > > #define virt_addr_valid(addr) ({ \ > > __typeof__(addr) __addr = __tag_reset(addr); \ > > - __is_lm_address(__addr) && pfn_valid(virt_to_pfn(__addr)); \ > > + __is_lm_address(__addr) && pfn_is_map_memory(virt_to_pfn(__addr)); \ > > }) > > void dump_mem_limit(void); > > diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h > > index 012cffc574e8..99a6da91f870 100644 > > --- a/arch/arm64/include/asm/page.h > > +++ b/arch/arm64/include/asm/page.h > > @@ -38,6 +38,7 @@ void copy_highpage(struct page *to, struct page *from); > > typedef struct page *pgtable_t; > > extern int pfn_valid(unsigned long); > > +extern int pfn_is_map_memory(unsigned long); > > #include > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > > index 8711894db8c2..23dd99e29b23 100644 > > --- a/arch/arm64/kvm/mmu.c > > +++ b/arch/arm64/kvm/mmu.c > > @@ -85,7 +85,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm) > > static bool kvm_is_device_pfn(unsigned long pfn) > > { > > - return !pfn_valid(pfn); > > + return !pfn_is_map_memory(pfn); > > } > > /* > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > > index 3685e12aba9b..c54e329aca15 100644 > > --- a/arch/arm64/mm/init.c > > +++ b/arch/arm64/mm/init.c > > @@ -258,6 +258,12 @@ int pfn_valid(unsigned long pfn) > > } > > EXPORT_SYMBOL(pfn_valid); > > +int pfn_is_map_memory(unsigned long pfn) > > +{ > > I think you might have to add (see pfn_valid()) > > if (PHYS_PFN(PFN_PHYS(pfn)) != pfn) > return 0; > > to catch false positives. Yeah, makes sense. > > + return memblock_is_map_memory(PFN_PHYS(pfn)); > > +} > > +EXPORT_SYMBOL(pfn_is_map_memory); > > + > > static phys_addr_t memory_limit = PHYS_ADDR_MAX; > > /* > > diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c > > index b5e83c46b23e..b7c81dacabf0 100644 > > --- a/arch/arm64/mm/ioremap.c > > +++ b/arch/arm64/mm/ioremap.c > > @@ -43,7 +43,7 @@ static void __iomem *__ioremap_caller(phys_addr_t phys_addr, size_t size, > > /* > > * Don't allow RAM to be mapped. > > */ > > - if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr)))) > > + if (WARN_ON(pfn_is_map_memory(__phys_to_pfn(phys_addr)))) > > return NULL; > > area = get_vm_area_caller(size, VM_IOREMAP, caller); > > @@ -84,7 +84,7 @@ EXPORT_SYMBOL(iounmap); > > void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size) > > { > > /* For normal memory we already have a cacheable mapping. */ > > - if (pfn_valid(__phys_to_pfn(phys_addr))) > > + if (pfn_is_map_memory(__phys_to_pfn(phys_addr))) > > return (void __iomem *)__phys_to_virt(phys_addr); > > return __ioremap_caller(phys_addr, size, __pgprot(PROT_NORMAL), > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > > index 5d9550fdb9cf..26045e9adbd7 100644 > > --- a/arch/arm64/mm/mmu.c > > +++ b/arch/arm64/mm/mmu.c > > @@ -81,7 +81,7 @@ void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd) > > pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, > > unsigned long size, pgprot_t vma_prot) > > { > > - if (!pfn_valid(pfn)) > > + if (!pfn_is_map_memory(pfn)) > > return pgprot_noncached(vma_prot); > > else if (file->f_flags & O_SYNC) > > return pgprot_writecombine(vma_prot); > > > > As discussed, in the future it would be nice if we could just rely on the > memmap state. There are cases where pfn_is_map_memory() will now be slower > than pfn_valid() -- e.g., we don't check for valid_section() in case of > CONFIG_SPARSEMEM. This would apply where pfn_valid() would have returned > "0". > > As we're not creating the direct map, kern_addr_valid() shouldn't need love. > It'd be some kind of ugly if some generic code used by arm64 would be > relying in case of arm64 on pfn_valid() to return the expected result; I > doubt it. No doubt there is a room for further improvement in this area. > Acked-by: David Hildenbrand Thanks! -- Sincerely yours, Mike. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm