Re: [PATCH v6 20/76] x86/boot/compressed/64: Call set_sev_encryption_mask earlier
From: Borislav Petkov <bp@alien8.de>
Date: 2020-08-27 09:36:56
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kvm, lkml
On Mon, Aug 24, 2020 at 10:54:15AM +0200, Joerg Roedel wrote: Just minor style issues to be fixed by committer or in case you have to send a new version: Subject: Re: [PATCH v6 20/76] x86/boot/compressed/64: Call set_sev_encryption_mask earlier set_sev_encryption_mask() <- it is a function.
From: Joerg Roedel <redacted> Call set_sev_encryption_mask() while still on the stage 1 #VC-handler, because the stage 2 handler needs our own page-tables to be set up, to
"... needs the kernel's own page tables to be set up... " "we" is almost always ambiguous and should be avoided by formulating the commit message in passive voice.
quoted hunk ↗ jump to hunk
which calling set_sev_encryption_mask() is a prerequisite. Signed-off-by: Joerg Roedel <redacted> Link: https://lore.kernel.org/r/20200724160336.5435-20-joro@8bytes.org (local) --- arch/x86/boot/compressed/head_64.S | 8 +++++++- arch/x86/boot/compressed/ident_map_64.c | 3 --- 2 files changed, 7 insertions(+), 4 deletions(-)diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 013b29921836..c7fcf60cbd08 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S@@ -533,9 +533,15 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) rep stosq /* - * Load stage2 IDT and switch to our own page-table + * If running as an SEV guest, the encryption mask is required in the + * page-table setup code below. When the guest also has SEV-ES enabled + * set_sev_encryption_mask() will cause #VC exceptions, but the stage2 + * handler can't map its GHCB because the page-table is not set up yet. + * So set up the encryption mask here while still on the stage1 #VC + * handler. Then load stage2 IDT and switch to our own page-table.
... to the kernel's own page table."
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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