linux-kernel - Re: [PATCH RFC v9 02/51] KVM: x86: Add gmem hook for invalidating private memory

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Date:   Mon, 12 Jun 2023 12:49:05 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Michael Roth <michael.roth@....com>
Cc:     kvm@...r.kernel.org, linux-coco@...ts.linux.dev,
        linux-mm@...ck.org, linux-crypto@...r.kernel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        jroedel@...e.de, thomas.lendacky@....com, hpa@...or.com,
        ardb@...nel.org, pbonzini@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, jmattson@...gle.com, luto@...nel.org,
        dave.hansen@...ux.intel.com, slp@...hat.com, pgonda@...gle.com,
        peterz@...radead.org, srinivas.pandruvada@...ux.intel.com,
        rientjes@...gle.com, dovmurik@...ux.ibm.com, tobin@....com,
        vbabka@...e.cz, kirill@...temov.name, ak@...ux.intel.com,
        tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, alpergun@...gle.com,
        dgilbert@...hat.com, jarkko@...nel.org, ashish.kalra@....com,
        nikunj.dadhania@....com, liam.merwick@...cle.com,
        zhi.a.wang@...el.com
Subject: Re: [PATCH RFC v9 02/51] KVM: x86: Add gmem hook for invalidating
 private memory

On Sun, Jun 11, 2023 at 11:25:10PM -0500, Michael Roth wrote:
> TODO: add a CONFIG option that can be to completely skip arch
> invalidation loop and avoid __weak references for arch/platforms that
> don't need an additional invalidation hook.
> 
> In some cases, like with SEV-SNP, guest memory needs to be updated in a
> platform-specific manner before it can be safely freed back to the host.
> Add hooks to wire up handling of this sort when freeing memory in
> response to FALLOC_FL_PUNCH_HOLE operations.
> 
> Also issue invalidations of all allocated pages when releasing the gmem
> file so that the pages are not left in an unusable state when they get
> freed back to the host.
> 
> Signed-off-by: Michael Roth <michael.roth@....com>
> ---
>  arch/x86/include/asm/kvm-x86-ops.h |  1 +
>  arch/x86/include/asm/kvm_host.h    |  1 +
>  arch/x86/kvm/x86.c                 |  6 ++++
>  include/linux/kvm_host.h           |  3 ++
>  virt/kvm/guest_mem.c               | 48 ++++++++++++++++++++++++++++--
>  5 files changed, 57 insertions(+), 2 deletions(-)

ld: arch/x86/kvm/../../../virt/kvm/eventfd.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/../../../virt/kvm/binary_stats.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/arch/x86/kvm/../../../virt/kvm/binary_stats.c:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/../../../virt/kvm/vfio.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/../../../virt/kvm/coalesced_mmio.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/../../../virt/kvm/async_pf.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/../../../virt/kvm/irqchip.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/../../../virt/kvm/dirty_ring.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/../../../virt/kvm/pfncache.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/x86.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/emulate.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/i8259.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/irq.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/lapic.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/i8254.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/ioapic.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/irq_comm.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/cpuid.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/pmu.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/mtrr.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/hyperv.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/debugfs.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/mmu/mmu.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/mmu/page_track.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/mmu/spte.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/mmu/tdp_iter.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/arch/x86/kvm/mmu/tdp_iter.c:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/mmu/tdp_mmu.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
ld: arch/x86/kvm/smm.o: in function `kvm_arch_gmem_invalidate':
/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: multiple definition of `kvm_arch_gmem_invalidate'; arch/x86/kvm/../../../virt/kvm/kvm_main.o:/home/boris/kernel/2nd/linux/./include/linux/kvm_host.h:2356: first defined here
make[3]: *** [scripts/Makefile.build:452: arch/x86/kvm/kvm.o] Error 1
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [scripts/Makefile.build:494: arch/x86/kvm] Error 2
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [scripts/Makefile.build:494: arch/x86] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:2028: .] Error 2

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette