From: Yan Zhao <yan.y.zhao@intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"jgg@nvidia.com" <jgg@nvidia.com>,
"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"seanjc@google.com" <seanjc@google.com>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"luto@kernel.org" <luto@kernel.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>, "hpa@zytor.com" <hpa@zytor.com>,
"corbet@lwn.net" <corbet@lwn.net>,
"joro@8bytes.org" <joro@8bytes.org>,
"will@kernel.org" <will@kernel.org>,
"robin.murphy@arm.com" <robin.murphy@arm.com>,
"baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>
Subject: Re: [PATCH 2/5] KVM: x86/mmu: Fine-grained check of whether a invalid & RAM PFN is MMIO
Date: Tue, 7 May 2024 17:19:13 +0800 [thread overview]
Message-ID: <ZjnyEQilJRK97HVB@yzhao56-desk.sh.intel.com> (raw)
In-Reply-To: <BN9PR11MB5276CABD8B3E1772932E2E3D8CE42@BN9PR11MB5276.namprd11.prod.outlook.com>
On Tue, May 07, 2024 at 04:39:27PM +0800, Tian, Kevin wrote:
> > From: Zhao, Yan Y <yan.y.zhao@intel.com>
> > Sent: Tuesday, May 7, 2024 2:20 PM
> > @@ -101,9 +101,21 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
> > */
> > (!pat_enabled() ||
> > pat_pfn_immune_to_uc_mtrr(pfn));
> >
> > + /*
> > + * If the PFN is invalid and not RAM in raw e820 table, keep treating it
> > + * as MMIO.
> > + *
> > + * If the PFN is invalid and is RAM in raw e820 table,
> > + * - if PAT is not enabled, always treat the PFN as MMIO to avoid
> > futher
> > + * checking of MTRRs.
> > + * - if PAT is enabled, treat the PFN as MMIO if its PAT is UC/WC/UC-
> > in
> > + * primary MMU.
> > + * to prevent guest cacheable access to MMIO PFNs.
> > + */
> > return !e820__mapped_raw_any(pfn_to_hpa(pfn),
> > pfn_to_hpa(pfn + 1) - 1,
> > - E820_TYPE_RAM);
> > + E820_TYPE_RAM) ? true :
> > + (!pat_enabled() ||
> > pat_pfn_immune_to_uc_mtrr(pfn));
>
> Is it for another theoretical problem in case the primary
> mmu uses a non-WB type on a invalid RAM-type pfn so
> you want to do additional scrutiny here?
Yes. Another untold reason is that patch 3 does not do CLFLUSH to this type of
memory since it's mapped as uncacheable in primary MMU. I feel that it's better
to ensure guest will not access it in cacheable memory type either.
next prev parent reply other threads:[~2024-05-07 9:20 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-07 6:18 [PATCH 0/5] Enforce CPU cache flush for non-coherent device assignment Yan Zhao
2024-05-07 6:19 ` [PATCH 1/5] x86/pat: Let pat_pfn_immune_to_uc_mtrr() check MTRR for untracked PAT range Yan Zhao
2024-05-07 8:26 ` Tian, Kevin
2024-05-07 9:12 ` Yan Zhao
2024-05-08 22:14 ` Alex Williamson
2024-05-09 3:36 ` Yan Zhao
2024-05-16 7:42 ` Tian, Kevin
2024-05-16 14:07 ` Sean Christopherson
2024-05-20 2:36 ` Tian, Kevin
2024-05-07 6:20 ` [PATCH 2/5] KVM: x86/mmu: Fine-grained check of whether a invalid & RAM PFN is MMIO Yan Zhao
2024-05-07 8:39 ` Tian, Kevin
2024-05-07 9:19 ` Yan Zhao [this message]
2024-05-07 6:20 ` [PATCH 3/5] x86/mm: Introduce and export interface arch_clean_nonsnoop_dma() Yan Zhao
2024-05-07 8:51 ` Tian, Kevin
2024-05-07 9:40 ` Yan Zhao
2024-05-20 14:07 ` Christoph Hellwig
2024-05-21 15:49 ` Jason Gunthorpe
2024-05-21 16:00 ` Jason Gunthorpe
2024-05-22 3:41 ` Yan Zhao
2024-05-28 6:37 ` Christoph Hellwig
2024-06-01 19:46 ` Jason Gunthorpe
2024-06-06 2:48 ` Yan Zhao
2024-06-06 11:55 ` Jason Gunthorpe
2024-06-07 9:39 ` Yan Zhao
2024-05-07 6:21 ` [PATCH 4/5] vfio/type1: Flush CPU caches on DMA pages in non-coherent domains Yan Zhao
2024-05-09 18:10 ` Alex Williamson
2024-05-10 10:31 ` Yan Zhao
2024-05-10 16:57 ` Alex Williamson
2024-05-13 7:11 ` Yan Zhao
2024-05-16 7:53 ` Tian, Kevin
2024-05-16 8:34 ` Tian, Kevin
2024-05-16 20:31 ` Alex Williamson
2024-05-17 17:11 ` Jason Gunthorpe
2024-05-20 2:52 ` Tian, Kevin
2024-05-21 16:07 ` Jason Gunthorpe
2024-05-21 16:21 ` Alex Williamson
2024-05-21 16:34 ` Jason Gunthorpe
2024-05-21 18:19 ` Alex Williamson
2024-05-21 18:37 ` Jason Gunthorpe
2024-05-22 6:24 ` Tian, Kevin
2024-05-22 12:29 ` Jason Gunthorpe
2024-05-22 14:43 ` Alex Williamson
2024-05-22 16:52 ` Jason Gunthorpe
2024-05-22 18:22 ` Alex Williamson
2024-05-22 23:26 ` Tian, Kevin
2024-05-22 23:32 ` Jason Gunthorpe
2024-05-22 23:40 ` Tian, Kevin
2024-05-23 14:58 ` Jason Gunthorpe
2024-05-23 22:47 ` Alex Williamson
2024-05-24 0:30 ` Tian, Kevin
2024-05-24 13:50 ` Jason Gunthorpe
2024-05-22 3:33 ` Yan Zhao
2024-05-22 3:24 ` Yan Zhao
2024-05-22 12:26 ` Jason Gunthorpe
2024-05-24 3:07 ` Yan Zhao
2024-05-16 20:50 ` Alex Williamson
2024-05-17 3:11 ` Yan Zhao
2024-05-17 4:44 ` Alex Williamson
2024-05-17 5:00 ` Yan Zhao
2024-05-07 6:22 ` [PATCH 5/5] iommufd: " Yan Zhao
2024-05-09 14:13 ` Jason Gunthorpe
2024-05-10 8:03 ` Yan Zhao
2024-05-10 13:29 ` Jason Gunthorpe
2024-05-13 7:43 ` Yan Zhao
2024-05-14 15:11 ` Jason Gunthorpe
2024-05-15 7:06 ` Yan Zhao
2024-05-15 20:43 ` Jason Gunthorpe
2024-05-16 2:32 ` Yan Zhao
2024-05-16 8:38 ` Tian, Kevin
2024-05-16 9:48 ` Yan Zhao
2024-05-17 17:04 ` Jason Gunthorpe
2024-05-20 2:45 ` Yan Zhao
2024-05-21 16:04 ` Jason Gunthorpe
2024-05-22 3:17 ` Yan Zhao
2024-05-22 6:29 ` Yan Zhao
2024-05-22 17:01 ` Jason Gunthorpe
2024-05-27 7:15 ` Yan Zhao
2024-06-01 16:48 ` Jason Gunthorpe
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