[PATCH 40/62] x86/sev-es: Filter exceptions not supported from user-space
From: Joerg Roedel <joro@8bytes.org>
Date: 2020-02-11 13:53:36
Also in:
kvm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Joerg Roedel <redacted> Currently only CPUID caused #VC exceptions are supported from user-space. Filter the others out early. Signed-off-by: Joerg Roedel <redacted> --- arch/x86/kernel/sev-es.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index d128a9397639..84b5b8f7897a 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c@@ -209,6 +209,26 @@ static enum es_result handle_vc_exception(struct es_em_ctxt *ctxt, return result; } +static enum es_result context_filter(struct pt_regs *regs, long exit_code) +{ + enum es_result r = ES_OK; + + if (user_mode(regs)) { + switch (exit_code) { + /* List of #VC exit-codes we support in user-space */ + case SVM_EXIT_EXCP_BASE ... SVM_EXIT_LAST_EXCP: + case SVM_EXIT_CPUID: + r = ES_OK; + break; + default: + r = ES_UNSUPPORTED; + break; + } + } + + return r; +} + static void forward_exception(struct es_em_ctxt *ctxt) { long error_code = ctxt->fi.error_code;
@@ -245,6 +265,10 @@ dotraplinkage void do_vmm_communication(struct pt_regs *regs, unsigned long exit ghcb_invalidate(ghcb); result = init_em_ctxt(&ctxt, regs, exit_code); + /* Check if the exception is supported in the context we came from. */ + if (result == ES_OK) + result = context_filter(regs, exit_code); + if (result == ES_OK) result = handle_vc_exception(&ctxt, ghcb, exit_code);
--
2.17.1