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Message-ID: <20240319134219.evphel2bmyopdz75@amd.com>
Date: Tue, 19 Mar 2024 08:42:19 -0500
From: Michael Roth <michael.roth@....com>
To: Paolo Bonzini <pbonzini@...hat.com>
CC: <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
<isaku.yamahata@...el.com>, <seanjc@...gle.com>, Dave Hansen
<dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v4 09/15] KVM: SEV: sync FPU and AVX state at
LAUNCH_UPDATE_VMSA time
On Mon, Mar 18, 2024 at 07:33:46PM -0400, Paolo Bonzini wrote:
> SEV-ES allows passing custom contents for x87, SSE and AVX state into the VMSA.
> Allow userspace to do that with the usual KVM_SET_XSAVE API and only mark
> FPU contents as confidential after it has been copied and encrypted into
> the VMSA.
>
> Since the XSAVE state for AVX is the first, it does not need the
> compacted-state handling of get_xsave_addr(). However, there are other
> parts of XSAVE state in the VMSA that currently are not handled, and
> the validation logic of get_xsave_addr() is pointless to duplicate
> in KVM, so move get_xsave_addr() to public FPU API; it is really just
> a facility to operate on XSAVE state and does not expose any internal
> details of arch/x86/kernel/fpu.
>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
> arch/x86/include/asm/fpu/api.h | 3 +++
> arch/x86/kernel/fpu/xstate.h | 2 --
> arch/x86/kvm/svm/sev.c | 36 ++++++++++++++++++++++++++++++++++
> arch/x86/kvm/svm/svm.c | 8 --------
> 4 files changed, 39 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
> index a2be3aefff9f..f86ad3335529 100644
> --- a/arch/x86/include/asm/fpu/api.h
> +++ b/arch/x86/include/asm/fpu/api.h
> @@ -143,6 +143,9 @@ extern void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfe
>
> extern u64 xstate_get_guest_group_perm(void);
>
> +extern void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
I get a linker error if I don't add an EXPORT_SYMBOL_GPL(get_xsave_addr)
-Mike
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