diff options
| author | Tom Lendacky <[email protected]> | 2020-09-07 15:15:55 +0200 |
|---|---|---|
| committer | Borislav Petkov <[email protected]> | 2020-09-09 11:33:20 +0200 |
| commit | 4711e7acaa125d8cc242f06e1f4d6c74e177454b (patch) | |
| tree | 7bc55a6cbc7294f14fdbbc28a39239f6aef1f293 | |
| parent | a14a92fc4b420ae6713800a8ae8c3686c1a1fa20 (diff) | |
x86/sev-es: Handle RDTSC(P) Events
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 uses RDTSC/RDTSCP to gather entropy and some
hypervisors intercept these instructions.
Signed-off-by: Tom Lendacky <[email protected]>
[ [email protected]: - Adapt to #VC handling infrastructure
- Make it available early ]
Co-developed-by: Joerg Roedel <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
| -rw-r--r-- | arch/x86/boot/compressed/sev-es.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/sev-es-shared.c | 23 | ||||
| -rw-r--r-- | arch/x86/kernel/sev-es.c | 4 |
3 files changed, 31 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/sev-es.c b/arch/x86/boot/compressed/sev-es.c index b1790f487456..5f15e5864e0c 100644 --- a/arch/x86/boot/compressed/sev-es.c +++ b/arch/x86/boot/compressed/sev-es.c @@ -181,6 +181,10 @@ 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 491b557bdfba..4be8af2f9c57 100644 --- a/arch/x86/kernel/sev-es-shared.c +++ b/arch/x86/kernel/sev-es-shared.c @@ -467,3 +467,26 @@ 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_rax_is_valid(ghcb) && ghcb_rdx_is_valid(ghcb) && + (!rdtscp || ghcb_rcx_is_valid(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 aba27c3c1633..4d468ec325c3 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -866,6 +866,10 @@ 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; |