[PATCH v3 56/75] x86/sev-es: Handle RDTSC(P) Events
From: Joerg Roedel <joro@8bytes.org>
Date: 2020-04-28 15:20:34
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: Tom Lendacky <thomas.lendacky@amd.com>
Implement a handler for #VC exceptions caused by RDTSC and RDTSCP
instructions. Also make it available in the pre-decompression stage
because the KASLR code used RDTSC/RDTSCP to gather entropy and some
hypervisors intercept these instructions.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
[ jroedel@suse.de: - Adapt to #VC handling infrastructure
- Make it available early ]
Co-developed-by: Joerg Roedel <redacted>
Signed-off-by: Joerg Roedel <redacted>
---
arch/x86/boot/compressed/sev-es.c | 4 ++++
arch/x86/kernel/sev-es-shared.c | 23 +++++++++++++++++++++++
arch/x86/kernel/sev-es.c | 4 ++++
3 files changed, 31 insertions(+)
diff --git a/arch/x86/boot/compressed/sev-es.c b/arch/x86/boot/compressed/sev-es.c
index 05ba1dcdd103..12a5d918d837 100644
--- a/arch/x86/boot/compressed/sev-es.c
+++ b/arch/x86/boot/compressed/sev-es.c@@ -180,6 +180,10 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code) goto finish; switch (exit_code) { + case SVM_EXIT_RDTSC: + case SVM_EXIT_RDTSCP: + result = vc_handle_rdtsc(boot_ghcb, &ctxt, exit_code); + break; case SVM_EXIT_IOIO: result = vc_handle_ioio(boot_ghcb, &ctxt); break;
diff --git a/arch/x86/kernel/sev-es-shared.c b/arch/x86/kernel/sev-es-shared.c
index 3d645662ff10..5bfc1f3030d4 100644
--- a/arch/x86/kernel/sev-es-shared.c
+++ b/arch/x86/kernel/sev-es-shared.c@@ -454,3 +454,26 @@ static enum es_result vc_handle_cpuid(struct ghcb *ghcb, return ES_OK; } + +static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, + struct es_em_ctxt *ctxt, + unsigned long exit_code) +{ + bool rdtscp = (exit_code == SVM_EXIT_RDTSCP); + enum es_result ret; + + ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0); + if (ret != ES_OK) + return ret; + + if (!(ghcb_is_valid_rax(ghcb) && ghcb_is_valid_rdx(ghcb) && + (!rdtscp || ghcb_is_valid_rcx(ghcb)))) + return ES_VMM_ERROR; + + ctxt->regs->ax = ghcb->save.rax; + ctxt->regs->dx = ghcb->save.rdx; + if (rdtscp) + ctxt->regs->cx = ghcb->save.rcx; + + return ES_OK; +}
diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index a8c0d865ca22..8b2afb9e292d 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c@@ -818,6 +818,10 @@ static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt, case SVM_EXIT_WRITE_DR7: result = vc_handle_dr7_write(ghcb, ctxt); break; + case SVM_EXIT_RDTSC: + case SVM_EXIT_RDTSCP: + result = vc_handle_rdtsc(ghcb, ctxt, exit_code); + break; case SVM_EXIT_CPUID: result = vc_handle_cpuid(ghcb, ctxt); break;
--
2.17.1