Messages in this thread | | | Date | Mon, 26 Oct 2020 19:27:06 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v3 1/5] x86/boot/compressed/64: Introduce sev_status |
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On Wed, Oct 21, 2020 at 02:39:34PM +0200, Joerg Roedel wrote: > From: Joerg Roedel <jroedel@suse.de> > > Introduce sev_status and initialize it together with sme_me_mask to have > an indicator which SEV features are enabled. > > Signed-off-by: Joerg Roedel <jroedel@suse.de> > --- > arch/x86/boot/compressed/mem_encrypt.S | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/boot/compressed/mem_encrypt.S b/arch/x86/boot/compressed/mem_encrypt.S > index dd07e7b41b11..2192b3bd78d8 100644 > --- a/arch/x86/boot/compressed/mem_encrypt.S > +++ b/arch/x86/boot/compressed/mem_encrypt.S > @@ -81,6 +81,13 @@ SYM_FUNC_START(set_sev_encryption_mask) > > bts %rax, sme_me_mask(%rip) /* Create the encryption mask */ > > + /* Read sev_status */ > + movl $MSR_AMD64_SEV, %ecx > + rdmsr > + shlq $32, %rdx > + orq %rdx, %rax > + movq %rax, sev_status(%rip)
A couple of lines above you call get_sev_encryption_bit() which already reads MSR_AMD64_SEV. Why not set sev_status there too instead of reading that MSR again here?
It can read that MSR once and use sev_status(%rip) from then on to avoid reading that MSR multiple times...
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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