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Message-ID: <20230106130021.00006c94@gmail.com>
Date: Fri, 6 Jan 2023 13:00:21 +0200
From: Zhi Wang <zhi.wang.linux@...il.com>
To: Dexuan Cui <decui@...rosoft.com>
Cc: ak@...ux.intel.com, arnd@...db.de, bp@...en8.de,
brijesh.singh@....com, dan.j.williams@...el.com,
dave.hansen@...ux.intel.com, haiyangz@...rosoft.com, hpa@...or.com,
jane.chu@...cle.com, kirill.shutemov@...ux.intel.com,
kys@...rosoft.com, linux-arch@...r.kernel.org,
linux-hyperv@...r.kernel.org, luto@...nel.org, mingo@...hat.com,
peterz@...radead.org, rostedt@...dmis.org,
sathyanarayanan.kuppuswamy@...ux.intel.com, seanjc@...gle.com,
tglx@...utronix.de, tony.luck@...el.com, wei.liu@...nel.org,
x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] Drivers: hv: vmbus: Support TDX guests
On Mon, 21 Nov 2022 11:51:51 -0800
Dexuan Cui <decui@...rosoft.com> wrote:
> Intel folks added the generic code to support a TDX guest in April, 2022.
> This commit and some earlier commits from me add the Hyper-V specific
> code so that a TDX guest can run on Hyper-V.
>
> Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> ---
> arch/x86/hyperv/hv_init.c | 19 +++++++++++++++----
> arch/x86/kernel/cpu/mshyperv.c | 10 ++++++++++
> arch/x86/mm/pat/set_memory.c | 2 +-
> drivers/hv/connection.c | 4 +++-
> drivers/hv/hv.c | 25 +++++++++++++++++++++++++
> drivers/hv/ring_buffer.c | 2 +-
> 6 files changed, 55 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 05682c4e327f..694f7fb04e5d 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -77,7 +77,7 @@ static int hyperv_init_ghcb(void)
> static int hv_cpu_init(unsigned int cpu)
> {
> union hv_vp_assist_msr_contents msr = { 0 };
> - struct hv_vp_assist_page **hvp =
> &hv_vp_assist_page[smp_processor_id()];
> + struct hv_vp_assist_page **hvp;
> int ret;
>
> ret = hv_common_cpu_init(cpu);
> @@ -87,6 +87,7 @@ static int hv_cpu_init(unsigned int cpu)
> if (!hv_vp_assist_page)
> return 0;
>
> + hvp = &hv_vp_assist_page[smp_processor_id()];
> if (!*hvp) {
> if (hv_root_partition) {
> /*
> @@ -398,11 +399,21 @@ void __init hyperv_init(void)
> if (hv_common_init())
> return;
>
> - hv_vp_assist_page = kcalloc(num_possible_cpus(),
> - sizeof(*hv_vp_assist_page),
> GFP_KERNEL);
> + /*
> + * The VP assist page is useless to a TDX guest: the only use we
> + * would have for it is lazy EOI, which can not be used with
> TDX.
> + */
> + if (hv_isolation_type_tdx())
> + hv_vp_assist_page = NULL;
> + else
> + hv_vp_assist_page = kcalloc(num_possible_cpus(),
> + sizeof(*hv_vp_assist_page),
> + GFP_KERNEL);
> if (!hv_vp_assist_page) {
> ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
> - goto common_free;
> +
> + if (!hv_isolation_type_tdx())
> + goto common_free;
> }
>
> if (hv_isolation_type_snp()) {
> diff --git a/arch/x86/kernel/cpu/mshyperv.c
> b/arch/x86/kernel/cpu/mshyperv.c index dddccdbc5526..6f597b23ad3e 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -350,7 +350,17 @@ static void __init ms_hyperv_init_platform(void)
> case HV_ISOLATION_TYPE_TDX:
> static_branch_enable(&isolation_type_tdx);
>
> + cc_set_vendor(CC_VENDOR_INTEL);
> +
> ms_hyperv.shared_gpa_boundary =
> cc_mkdec(0); +
> + /* Don't use the unsafe Hyper-V TSC
> page */
> + ms_hyperv.features &=
> + ~HV_MSR_REFERENCE_TSC_AVAILABLE;
> +
> + /* HV_REGISTER_CRASH_CTL is unsupported
> */
> + ms_hyperv.misc_features &=
> +
> ~HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE; break;
>
> default:
> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
> index 2e5a045731de..bb44aaddb230 100644
> --- a/arch/x86/mm/pat/set_memory.c
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -2120,7 +2120,7 @@ static int __set_memory_enc_pgtable(unsigned long
> addr, int numpages, bool enc)
> static int __set_memory_enc_dec(unsigned long addr, int numpages, bool
> enc) {
> - if (hv_is_isolation_supported())
> + if (hv_is_isolation_supported() && !hv_isolation_type_tdx())
> return hv_set_mem_host_visibility(addr, numpages, !enc);
>
> if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
Let's say there will be four cases:
----
case a. SEV-SNP guest with paravisor
In the code, this case is represented by:
hv_is_isolation_supported() && hv_isolation_type_snp()
hv_is_isolation_supported() && !hv_isolation_type_tdx()
case b. TDX guest with paravisor
?
case c. SEV-SNP guest *without* paravisor
?
case d. TDX guest *without* paravisor
In the code, this case is represented by:
hv_is_isolation_supported() && hv_isolation_type_tdx()
----
1. It would be better to use "hv_is_isolation_supported() &&
hv_isolation_type_snp()" to represent case a to avoid confusion in the
above patch.
2. For now, hv_is_isolation_supported() only shows if the guest is a CC
guest or not. hv_isolation_type_*() only represent SNP or TDX but
not "w/ or w/o paravisor".
How are you going to represent case b and c in __set_memory_enc_dec()?
I think you are looking for something to show if the guest is running
with a paravisor or not here:
if (hv_is_isolation_supported() && hv_is_isolation_with_paravisor())
...
Thanks,
Zhi.
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index 9dc27e5d367a..1ecc3c29e3f7 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -250,12 +250,14 @@ int vmbus_connect(void)
> * Isolation VM with AMD SNP needs to access monitor
> page via
> * address space above shared gpa boundary.
> */
> - if (hv_isolation_type_snp()) {
> + if (hv_isolation_type_snp() || hv_isolation_type_tdx())
> { vmbus_connection.monitor_pages_pa[0] +=
> ms_hyperv.shared_gpa_boundary;
> vmbus_connection.monitor_pages_pa[1] +=
> ms_hyperv.shared_gpa_boundary;
> + }
>
> + if (hv_isolation_type_snp()) {
> vmbus_connection.monitor_pages[0]
> =
> memremap(vmbus_connection.monitor_pages_pa[0], HV_HYP_PAGE_SIZE,
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 4d6480d57546..03b3257bc1ab 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -18,6 +18,7 @@
> #include <linux/clockchips.h>
> #include <linux/delay.h>
> #include <linux/interrupt.h>
> +#include <linux/set_memory.h>
> #include <clocksource/hyperv_timer.h>
> #include <asm/mshyperv.h>
> #include "hyperv_vmbus.h"
> @@ -119,6 +120,7 @@ int hv_synic_alloc(void)
> {
> int cpu;
> struct hv_per_cpu_context *hv_cpu;
> + int ret;
>
> /*
> * First, zero all per-cpu memory areas so hv_synic_free() can
> @@ -168,6 +170,21 @@ int hv_synic_alloc(void)
> pr_err("Unable to allocate post msg page\n");
> goto err;
> }
> +
> +
> + if (hv_isolation_type_tdx()) {
> + ret = set_memory_decrypted(
> + (unsigned
> long)hv_cpu->synic_message_page, 1);
> + BUG_ON(ret);
> +
> + ret = set_memory_decrypted(
> + (unsigned
> long)hv_cpu->synic_event_page, 1);
> + BUG_ON(ret);
> +
> + ret = set_memory_decrypted(
> + (unsigned long)hv_cpu->post_msg_page,
> 1);
> + BUG_ON(ret);
> + }
> }
>
> return 0;
> @@ -225,6 +242,10 @@ void hv_synic_enable_regs(unsigned int cpu)
> } else {
> simp.base_simp_gpa =
> virt_to_phys(hv_cpu->synic_message_page)
> >> HV_HYP_PAGE_SHIFT;
> +
> + if (hv_isolation_type_tdx())
> + simp.base_simp_gpa +=
> ms_hyperv.shared_gpa_boundary
> + >> HV_HYP_PAGE_SHIFT;
> }
>
> hv_set_register(HV_REGISTER_SIMP, simp.as_uint64);
> @@ -243,6 +264,10 @@ void hv_synic_enable_regs(unsigned int cpu)
> } else {
> siefp.base_siefp_gpa =
> virt_to_phys(hv_cpu->synic_event_page)
> >> HV_HYP_PAGE_SHIFT;
> +
> + if (hv_isolation_type_tdx())
> + siefp.base_siefp_gpa +=
> ms_hyperv.shared_gpa_boundary
> + >> HV_HYP_PAGE_SHIFT;
> }
>
> hv_set_register(HV_REGISTER_SIEFP, siefp.as_uint64);
> diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
> index c6692fd5ab15..a51da82316ce 100644
> --- a/drivers/hv/ring_buffer.c
> +++ b/drivers/hv/ring_buffer.c
> @@ -233,7 +233,7 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info
> *ring_info,
> ring_info->ring_buffer = (struct hv_ring_buffer *)
> vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP,
> - PAGE_KERNEL);
> + pgprot_decrypted(PAGE_KERNEL_NOENC));
>
> kfree(pages_wraparound);
> if (!ring_info->ring_buffer)
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