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From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: "peterz@infradead.org" <peterz@infradead.org>,
	"jmattson@google.com" <jmattson@google.com>,
	"Christopherson, Sean J" <sean.j.christopherson@intel.com>,
	"vkuznets@redhat.com" <vkuznets@redhat.com>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	"joro@8bytes.org" <joro@8bytes.org>,
	"luto@kernel.org" <luto@kernel.org>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"wanpengli@tencent.com" <wanpengli@tencent.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"kirill.shutemov@linux.intel.com"
	<kirill.shutemov@linux.intel.com>,
	"keescook@chromium.org" <keescook@chromium.org>,
	"rppt@kernel.org" <rppt@kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"aarcange@redhat.com" <aarcange@redhat.com>,
	"liran.alon@oracle.com" <liran.alon@oracle.com>,
	"wad@chromium.org" <wad@chromium.org>,
	"rientjes@google.com" <rientjes@google.com>,
	"Kleen, Andi" <andi.kleen@intel.com>
Subject: Re: [RFCv2 14/16] KVM: Handle protected memory in __kvm_map_gfn()/__kvm_unmap_gfn()
Date: Thu, 22 Oct 2020 15:06:45 +0300	[thread overview]
Message-ID: <20201022120645.vdmytvcmdoku73os@box> (raw)
In-Reply-To: <8404a8802dbdbf81c8f75249039580f9e6942095.camel@intel.com>

On Wed, Oct 21, 2020 at 06:50:28PM +0000, Edgecombe, Rick P wrote:
> On Tue, 2020-10-20 at 09:18 +0300, Kirill A. Shutemov wrote:
> > @@ -467,7 +477,7 @@ void iounmap(volatile void __iomem *addr)
> >  	p = find_vm_area((void __force *)addr);
> >  
> >  	if (!p) {
> > -		printk(KERN_ERR "iounmap: bad address %p\n", addr);
> > +		printk(KERN_ERR "iounmap: bad address %px\n", addr);
> 
> Unintentional?

Yep. Will fix.

> > @@ -2162,15 +2178,20 @@ static int __kvm_map_gfn(struct kvm_memslots
> > *slots, gfn_t gfn,
> >  			kvm_cache_gfn_to_pfn(slot, gfn, cache, gen);
> >  		}
> >  		pfn = cache->pfn;
> > +		protected = cache->protected;
> >  	} else {
> >  		if (atomic)
> >  			return -EAGAIN;
> > -		pfn = gfn_to_pfn_memslot(slot, gfn);
> > +		pfn = gfn_to_pfn_memslot_protected(slot, gfn,
> > &protected);
> >  	}
> >  	if (is_error_noslot_pfn(pfn))
> >  		return -EINVAL;
> >  
> > -	if (pfn_valid(pfn)) {
> > +	if (protected) {
> > +		if (atomic)
> > +			return -EAGAIN;
> > +		hva = ioremap_cache_force(pfn_to_hpa(pfn), PAGE_SIZE);
> > +	} else if (pfn_valid(pfn)) {
> >  		page = pfn_to_page(pfn);
> >  		if (atomic)
> >  			hva = kmap_atomic(page);
> 
> I think the page could have got unmapped since the gup via the
> hypercall on another CPU. It could be an avenue for the guest to crash
> the host.

Hm.. I'm not sure I follow. Could you elaborate on what scenario you have
in mind?

-- 
 Kirill A. Shutemov


  reply	other threads:[~2020-10-22 12:06 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-20  6:18 [RFCv2 00/16] KVM protected memory extension Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 01/16] x86/mm: Move force_dma_unencrypted() to common code Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 02/16] x86/kvm: Introduce KVM memory protection feature Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 03/16] x86/kvm: Make DMA pages shared Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 04/16] x86/kvm: Use bounce buffers for KVM memory protection Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 05/16] x86/kvm: Make VirtIO use DMA API in KVM guest Kirill A. Shutemov
2020-10-20  8:06   ` Christoph Hellwig
2020-10-20 12:47     ` Kirill A. Shutemov
2020-10-22  3:31   ` Halil Pasic
2020-10-20  6:18 ` [RFCv2 06/16] x86/kvmclock: Share hvclock memory with the host Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 07/16] x86/realmode: Share trampoline area if KVM memory protection enabled Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 08/16] KVM: Use GUP instead of copy_from/to_user() to access guest memory Kirill A. Shutemov
2020-10-20  8:25   ` John Hubbard
2020-10-20 12:51     ` Kirill A. Shutemov
2020-10-22 11:49     ` Matthew Wilcox
2020-10-22 19:58       ` John Hubbard
2020-10-26  4:21         ` Matthew Wilcox
2020-10-26  4:44           ` John Hubbard
2020-10-26 13:28             ` Matthew Wilcox
2020-10-26 14:16               ` Jason Gunthorpe
2020-10-26 20:52               ` John Hubbard
2020-10-20 17:29   ` Ira Weiny
2020-10-22 11:37     ` Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 09/16] KVM: mm: Introduce VM_KVM_PROTECTED Kirill A. Shutemov
2020-10-21 18:47   ` Edgecombe, Rick P
2020-10-22 12:01     ` Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 10/16] KVM: x86: Use GUP for page walk instead of __get_user() Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 11/16] KVM: Protected memory extension Kirill A. Shutemov
2020-10-20  7:17   ` Peter Zijlstra
2020-10-20 12:55     ` Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 12/16] KVM: x86: Enabled protected " Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 13/16] KVM: Rework copy_to/from_guest() to avoid direct mapping Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 14/16] KVM: Handle protected memory in __kvm_map_gfn()/__kvm_unmap_gfn() Kirill A. Shutemov
2020-10-21 18:50   ` Edgecombe, Rick P
2020-10-22 12:06     ` Kirill A. Shutemov [this message]
2020-10-22 16:59       ` Edgecombe, Rick P
2020-10-23 10:36         ` Kirill A. Shutemov
2020-10-22  3:26   ` Halil Pasic
2020-10-22 12:07     ` Kirill A. Shutemov
2020-10-20  6:18 ` [RFCv2 15/16] KVM: Unmap protected pages from direct mapping Kirill A. Shutemov
2020-10-20  7:12   ` Peter Zijlstra
2020-10-20 12:18   ` David Hildenbrand
2020-10-20 13:20     ` David Hildenbrand
2020-10-21  1:20       ` Edgecombe, Rick P
2020-10-26 19:55     ` Tom Lendacky
2020-10-21 18:49   ` Edgecombe, Rick P
2020-10-23 12:37   ` Mike Rapoport
2020-10-23 16:32     ` Sean Christopherson
2020-10-20  6:18 ` [RFCv2 16/16] mm: Do not use zero page for VM_KVM_PROTECTED VMAs Kirill A. Shutemov
2020-10-20  7:46 ` [RFCv2 00/16] KVM protected memory extension Vitaly Kuznetsov
2020-10-20 13:49   ` Kirill A. Shutemov
2020-10-21 14:46     ` Vitaly Kuznetsov
2020-10-23 11:35       ` Kirill A. Shutemov
2020-10-23 12:01         ` Vitaly Kuznetsov
2020-10-21 18:20 ` Andy Lutomirski
2020-10-26 15:29   ` Kirill A. Shutemov
2020-10-26 23:58     ` Andy Lutomirski

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