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Message-Id: <20210413152217.3386288-2-ltykernel@gmail.com>
Date: Tue, 13 Apr 2021 11:22:06 -0400
From: Tianyu Lan <ltykernel@...il.com>
To: kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
wei.liu@...nel.org, tglx@...utronix.de, mingo@...hat.com,
bp@...en8.de, x86@...nel.org, hpa@...or.com, arnd@...db.de
Cc: Tianyu Lan <Tianyu.Lan@...rosoft.com>,
linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arch@...r.kernel.org, vkuznets@...hat.com,
thomas.lendacky@....com, brijesh.singh@....com,
sunilmut@...rosoft.com
Subject: [RFC V2 PATCH 1/12] x86/HV: Initialize GHCB page in Isolation VM
From: Tianyu Lan <Tianyu.Lan@...rosoft.com>
Hyper-V exposes GHCB page via SEV ES GHCB MSR for SNP guest
to communicate with hypervisor. Map GHCB page for all
cpus to read/write MSR register and submit hvcall request
via GHCB.
Signed-off-by: Tianyu Lan <Tianyu.Lan@...rosoft.com>
---
arch/x86/hyperv/hv_init.c | 52 +++++++++++++++++++++++++++++++---
include/asm-generic/mshyperv.h | 1 +
2 files changed, 49 insertions(+), 4 deletions(-)
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 0db5137d5b81..90e65fbf4c58 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -82,6 +82,9 @@ static int hv_cpu_init(unsigned int cpu)
struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
void **input_arg;
struct page *pg;
+ u64 ghcb_gpa;
+ void *ghcb_va;
+ void **ghcb_base;
/* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
pg = alloc_pages(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL, hv_root_partition ? 1 : 0);
@@ -128,6 +131,17 @@ static int hv_cpu_init(unsigned int cpu)
wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
}
+ if (ms_hyperv.ghcb_base) {
+ rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
+
+ ghcb_va = ioremap_cache(ghcb_gpa, HV_HYP_PAGE_SIZE);
+ if (!ghcb_va)
+ return -ENOMEM;
+
+ ghcb_base = (void **)this_cpu_ptr(ms_hyperv.ghcb_base);
+ *ghcb_base = ghcb_va;
+ }
+
return 0;
}
@@ -223,6 +237,7 @@ static int hv_cpu_die(unsigned int cpu)
unsigned long flags;
void **input_arg;
void *pg;
+ void **ghcb_va = NULL;
local_irq_save(flags);
input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
@@ -236,6 +251,13 @@ static int hv_cpu_die(unsigned int cpu)
*output_arg = NULL;
}
+ if (ms_hyperv.ghcb_base) {
+ ghcb_va = (void **)this_cpu_ptr(ms_hyperv.ghcb_base);
+ if (*ghcb_va)
+ iounmap(*ghcb_va);
+ *ghcb_va = NULL;
+ }
+
local_irq_restore(flags);
free_pages((unsigned long)pg, hv_root_partition ? 1 : 0);
@@ -372,6 +394,9 @@ void __init hyperv_init(void)
u64 guest_id, required_msrs;
union hv_x64_msr_hypercall_contents hypercall_msr;
int cpuhp, i;
+ u64 ghcb_gpa;
+ void *ghcb_va;
+ void **ghcb_base;
if (x86_hyper_type != X86_HYPER_MS_HYPERV)
return;
@@ -432,9 +457,24 @@ void __init hyperv_init(void)
VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
__builtin_return_address(0));
- if (hv_hypercall_pg == NULL) {
- wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
- goto remove_cpuhp_state;
+ if (hv_hypercall_pg == NULL)
+ goto clean_guest_os_id;
+
+ if (hv_isolation_type_snp()) {
+ ms_hyperv.ghcb_base = alloc_percpu(void *);
+ if (!ms_hyperv.ghcb_base)
+ goto clean_guest_os_id;
+
+ rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
+ ghcb_va = ioremap_cache(ghcb_gpa, HV_HYP_PAGE_SIZE);
+ if (!ghcb_va) {
+ free_percpu(ms_hyperv.ghcb_base);
+ ms_hyperv.ghcb_base = NULL;
+ goto clean_guest_os_id;
+ }
+
+ ghcb_base = (void **)this_cpu_ptr(ms_hyperv.ghcb_base);
+ *ghcb_base = ghcb_va;
}
rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
@@ -499,7 +539,8 @@ void __init hyperv_init(void)
return;
-remove_cpuhp_state:
+clean_guest_os_id:
+ wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
cpuhp_remove_state(cpuhp);
free_vp_assist_page:
kfree(hv_vp_assist_page);
@@ -528,6 +569,9 @@ void hyperv_cleanup(void)
*/
hv_hypercall_pg = NULL;
+ if (ms_hyperv.ghcb_base)
+ free_percpu(ms_hyperv.ghcb_base);
+
/* Reset the hypercall page */
hypercall_msr.as_uint64 = 0;
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index dff58a3db5d5..c6f4c5c20fb8 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -35,6 +35,7 @@ struct ms_hyperv_info {
u32 max_lp_index;
u32 isolation_config_a;
u32 isolation_config_b;
+ void __percpu **ghcb_base;
};
extern struct ms_hyperv_info ms_hyperv;
--
2.25.1
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