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Message-ID: <20070311103250.GA23396@elte.hu> Date: Sun, 11 Mar 2007 11:32:50 +0100 From: Ingo Molnar <mingo@...e.hu> To: Avi Kivity <avi@...ranet.com> Cc: kvm-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org Subject: Re: [kvm-devel] [PATCH] KVM: MMU: Fix guest writes to nonpae pde * Avi Kivity <avi@...ranet.com> wrote: > KVM shadow page tables are always in pae mode, regardless of the guest > setting. This means that a guest pde (mapping 4MB of memory) is > mapped to two shadow pdes (mapping 2MB each). > > When the guest writes to a pte or pde, we intercept the write and > emulate it. We also remove any shadowed mappings corresponding to the > write. Since the mmu did not account for the doubling in the number > of pdes, it removed the wrong entry, resulting in a mismatch between > shadow page tables and guest page tables, followed shortly by guest > memory corruption. > > This patch fixes the problem by detecting the special case of writing > to a non-pae pde and adjusting the address and number of shadow pdes > zapped accordingly. > > Signed-off-by: Avi Kivity <avi@...ranet.com> tested this with both PAE and non-PAE Linux host and guest - works fine. Acked-by: Ingo Molnar <mingo@...e.hu> Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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