linux-kernel - Re: [PATCH 5.4] KVM: x86: Fix pkru save/restore when guest CR4.PKE=0, move it to x86.c

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Date:   Sat, 23 May 2020 09:49:08 +0200
From:   Greg KH <greg@...ah.com>
To:     Babu Moger <babu.moger@....com>
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Subject: Re: [PATCH 5.4] KVM: x86: Fix pkru save/restore when guest
 CR4.PKE=0, move it to x86.c

On Fri, May 22, 2020 at 11:32:49AM -0500, Babu Moger wrote:
> [Backported upstream commit 37486135d3a7b03acc7755b63627a130437f066a]
> 
> Though rdpkru and wrpkru are contingent upon CR4.PKE, the PKRU
> resource isn't. It can be read with XSAVE and written with XRSTOR.
> So, if we don't set the guest PKRU value here(kvm_load_guest_xsave_state),
> the guest can read the host value.
> 
> In case of kvm_load_host_xsave_state, guest with CR4.PKE clear could
> potentially use XRSTOR to change the host PKRU value.
> 
> While at it, move pkru state save/restore to common code and the
> host_pkru field to kvm_vcpu_arch.  This will let SVM support protection keys.
> 
> Cc: stable@...r.kernel.org
> Reported-by: Jim Mattson <jmattson@...gle.com>
> Signed-off-by: Babu Moger <babu.moger@....com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>

Now applied, thanks.

greg k-h